Conservation – Page 27 – Shark Research & Conservation Program (SRC)

The Consequences of the Indo-Pacific Lionfish invasion into Atlantic Waters

February 26, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by Laurel Zaima, RJD intern

The introduction of an invasive species into a foreign ecosystem has dire and often unforeseen consequences. An invasive species is considered any living organism that is not native to the ecosystem and causes harm to the local environment (“Invasive Species”). Non-native organisms alter the ecosystem, which affects the native species, habitat structures, human health, and even our economy. Invasive species are actually one of the leading threats to native wildlife and are the primary risk to approximately 42% of threatened or endangered species (“Invasive Species”). The inevitable alteration to the ecosystem from the invasive species causes commercial, agricultural, and recreational activities to suffer. The current invasion of the lionfish is an extremely disconcerting issue that has been damaging and disrupting the native species and the balance of the ecosystem.

Lionfish are originally from the Indo-Pacific and Red Sea, but they have recently invaded Atlantic waters near Florida and the Caribbean and into the Gulf of Mexico (“Lionfish- Pterois volitans”). Lionfish were some of the most commonly imported tropical fish for aquariums; however, owners would often release them into the Atlantic when they grew too large for their aquariums (“Venomous Lionfish”). Lionfish were first reported off Florida’s Atlantic Coast near Dania Beach in 1985, and since then the lionfish populations have exponentially increased and spread (“Lionfish- Pterois volitans”). [Picture 1: In the summer of 2001, this lionfish was found about 40 miles off the coast of North Carolina.]

Lionfish have an extremely high success rate for a variety of reasons. Since the lionfish are not natively found in the Atlantic waters, they have no natural predators in this region to control their populations. Lionfish have 18 venomous spines that are used as a defense mechanism (“Lionfish- Pterois volitans”). Any native predators that have unknowingly tried to consume this new food source has fallen victim to their venomous spines. The lionfish also breed at a very rapid pace because both males and females sexually mature in less than a year and have the ability to spawn 12,000 to 15,000 eggs every four days in warm climates (“Lionfish- Pterois volitans”). Lionfish have quickly spread their populations throughout the Atlantic because are tolerant to a variety of habitat conditions. They have been found in shallow waters and in depths up to 1,000 feet; they can withstand temperatures as cold as 48 to 50 degrees; and they can survive in low salinities for short periods of time (“Lionfish- Pterois volitans”). Lionfish have easily assimilated into Atlantic waters, but the main concern about the lionfish is their broad diet that negatively impacted the native ecosystem.
Lionfish hurt the wellbeing of coral reefs because of their massive predation of native species, and they compete with the native predators for food. As a predatory reef fish, lionfish are known to prey on more than 70 marine and invertebrate species including yellowtail snapper, Nassau grouper, parrotfish, banded coral shrimp, and cleaner species (“Lionfish- Pterois volitans”). These feeding habits drastically reduce the native populations in coral reefs, which result in negative effects on the reef habitat. Some of the species targeted by the lionfish play important ecological roles in limiting the amount of algae on the reefs, and without their presence, the coral reefs can be overgrown by algae (“Lionfish- Pterois volitans”). Lionfish often target the native juvenile species as another source of food. Albins and Hixon (2008) found that lionfish caused significant reductions in the recruitment of native fish by an average of 79% over a 5-week study period. Targeting the coral-reef fish at the early stages of life declines the abundance and diversity of the local fish (Albins and Hixon, 2008). Complete eradication of lionfish from the Atlantic and Gulf of Mexico is probably unobtainable; however, efforts need to be made in order to control their rapidly growing populations.
There are a couple solutions that can be implemented towards the extermination of the invasion of lionfish. The first step that must be taken is to educate the public about lionfish in the Atlantic and Gulf of Mexico and the damaging effects they have on the natural ecosystem. Local fishermen should be encouraged to remove any lionfish that they catch to help limit the negative impact this species has on the native marine life (“Lionfish- Pterois volitans”). Commercial fisheries and recreational fishermen should also be encouraged to target lionfish as a main catch (Hixon, Albins, Redinger, 2009). When filleted and cooked properly, lionfish are very delicious. This species could be profitable to fisheries if they target to catch and sell them as a form of sustainable seafood. The recovery and maintenance of healthy populations of native predators, such as large grouper and sharks, can help regulate lionfish populations as well (Hixon, Albins, Redinger, 2009). Lionfish population controls can be regulated on a regional and nation wide level. Regions need to ensure that they are prioritizing the removal of lionfish from key areas such as marine protected areas (MPAs), high tourist areas, spawning aggregation sites, and nursery areas (Akins, 2012). These regions are extremely vulnerable to the lionfish, and an invasion by these predators could be detrimental to the recruitment and survival of local reef fish. A nation wide control effort of the lionfish in the Atlantic could help to reduce the lionfish in mass quantities (Akins, 2012). However, in order to monitor the progress of the nation’s control plan, commercial and recreational fishermen and scientists need to continue to report and document the lionfish caught in order to gauge the effectiveness of the implemented programs (Akins, 2012). [Picture 2: A Virgin Islands biological technician examines the Indo-Pacific lionfish captured off the coast.] By enacting some of these invasion control plans, the lionfish population can be better regulated, and the coral reefs and native species would be better preserved.
Works Cited
Akins JL (2012) Control Strategies: Tools and Techniques for Local Control. Pages 24-47 in: JA Morris Jr. (ed.) Invasive Lionfish: A Guide to Control and Management. Gulf and Caribbean Fisheries Institute Special Publication Series Number 1, Marathon, Florida USA. 113 pp.
Albins MA, Hixon MA (2008) Invasive Indo-Pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes. Mar Ecol Prog Ser 367: 233-238.
Hixon M, Albins M, Redinger T. “Lionfish Invasion: Super Predator Threatens Caribbean Coral Reefs.” NOAA’S Undersea Research Program. NOAA, 8 Mar. 2009. Web. 4 Feb. 2015.
“Invasive Species.” National Wildlife Federation. n.p. n.d. Web. 4 Feb. 2015.
“Lionfish- Pterois volitans.” Florida Fish and Wildlife Conservation Commission. n.p. n.d. Web. 4 Feb. 2015.
“Venomous Lionfish Invade South Florida Waters.” Lionfishhunters.org. n.p. 2010. Web. 4 Feb. 2015.

Exploitation and Cooperation by Cleaner Wrasse

February 20, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Laura Vander Meiden, RJD Intern

The relationship between cleaner wrasse and reef fish has long been one of the textbook examples of mutualism, a partnership in which both individuals benefit. In this relationship, the cleaner wrasses set up “cleaning stations” where they eat parasites and dead skin cells off of willing reef fish. The reef fish benefit through the removal of those parasites, while the wrasses gain a food source. However, the cleaner wrasses’ preferred food source is actually a type of mucus given off by the reef fish. Because of this, the cleaner wrasses sometimes deviate from mutualistic parasite removal by eating mucus given off by the client (Grutter et al 2003). This cheat disrupts the balance of the symbiotic interaction making participation detrimental to the reef fish that need the mucus for protection from bacteria and parasites. If this cheating behavior were to become the norm for cleaning wrasses, the reef fish would eventually stop participating because the partnership is no longer beneficial for them. Fortunately, both cleaner wrasse and reef fish have developed behaviors that limit the detrimental effects of cheating and keep the mutualistic relationship stable.

A cleaner wrasse and a moray eel. (picture by Albert Kok from wikimedia commons)

Non-predatory reef fish employ several different behaviors to keep the cleaner wrasse from sneaking bites of mucus. If there are multiple cleaner wrasse in the area, a fish who has had mucus stolen will immediately leave and visit another wrasse’s cleaning station. If there is only one wrasse in the area, the exploited fish will end the cleaning session and aggressively chase the wrasse. Both of these behaviors temporarily reduce the wrasse’s ability to feed by the termination of the session, and in the case of chasing behavior, are energetically intensive for the wrasse. Bshary et al (2005) has provided evidence that these two behaviors actually teach the wrasse to feed against their food preferences, limiting their mucus stealing. These two behaviors are called alternative control behaviors; they are termed such because non-predatory reef fish, the ones targeted by exploitation, have no option to cheat in this partnership, so instead they work to affect the outcome by these alternative means. Predatory reef fish on the other hand can reciprocate cheating behavior by eating the cleaner wrasse, it is likely for this reason that cleaner wrasse have not been observed to cheat in interaction with predatory reef fish (Bshary 2005).

These alternative control behaviors do not completely eradicate the cheating behaviors of cleaner wrasse. Instead, the cleaners have the ability to switch back and forth between mutualistic and parasitic behavior, based on the circumstances (Gingins 2013). The experimental conditions that were found to affect the cleaner’s decision to exploit were the level of temptation to cheat and the extent to which the partner employed alternative control behaviors. A higher level of temptation combined with a lack of controlling behaviors led to the highest level of exploitation while low temptation no matter the level of control behaviors utilized led to increased mutualism (Gingins 2013). Furthermore this ability to distinguish between different conditions was unique to cleaner wrasses. When a pinstripe wrasse, a non-cleaning wrasse species, was tested in the same situation it failed to adjust its behavior to the conditions(Gingins 2013). This is likely due to the fact that non-cleaning species have no reason to have evolved the cognitive capacity to decide when or when not to cheat.

Kelp bass and a cleaner wrasse. (Photo by Tomarin – wikimedia commons)

The back and forth between cleaners and reef fish may seem a bit excessive for what is supposed to be a mutually beneficial relationship. However, one has to realize that both the cleaner wrasse and the reef fish are focused on their own best interests. When these interests coincide with one another, the two are able to interact to the mutual benefit of all involved. When these interests do not coincide, such as when a cleaner wrasse attempts to cheat and eat mucus, the cooperation between the two will either disappear or strategies such as the reef fishes’ alternative control behaviors will develop. These behaviors decrease the benefits of the wrasse’s cheating behavior until it is in its own best interest to return to eating only ectoparasites and dead skin cells. Ultimately, the evolution of alternative control behaviors in this system has allowed for the continuance of this mutualistic behavior.

Works Cited

Bshary, R., & Grutter, A. S. (2005). Punishment and partner switching cause cooperative behaviour in a cleaning mutualism. Biology Letters, 1, 396-399.

Gingins, S., Werminghausen, J., Johnstone, R. A., Grutter, A. S., & Bshary, R. (2013). Power and temptation cause shifts between exploitation and cooperation in a cleaner wrasse mutualism. Proceedings of the Royal Society B: Biological Sciences, 280, 20130553-20130553.

Grutter, A. S., & Bshary, R. (2003). Cleaner wrasse prefer client mucus: support for partner control mechanisms in cleaning interactions. Proceedings of the Royal Society B: Biological Sciences,270, S242-S244.

Summary of “Competitive interactions for shelter between invasive Pacific red lionfish and native Nassau grouper”

February 11, 2015/0 Comments/in Conservation, Ocean News /by aanstett

Hannah Armstrong, RJD Intern

Invasive species have the potential to negatively effect normal ecological function in any environment. Marine biological invasions are increasingly common, most notably that of the Pacific red lionfish (Pterois volitans). While the lionfish invasion and its direct effects on native fish communities has been well researched, there has been little documented evidence regarding non-predatory interactions. In a 2014 study by Raymond, Albins and Pusack, they observed whether Pacific red lionfish and Nassau grouper, two species that occupy similar habitats, compete for shelter and whether or not the competition is size-dependent.

Pacific red lionfish (Pterois volitans) have been reported in the Atlantic Ocean since the mid-1980s and now pose a threat to the western Atlantic and Caribbean coral reef systems. As small-bodied predators, they are capable of significantly reducing the abundance and diversity of native fishes via predation. Nassau groupers (Epinephelus striatus), despite being regionally endangered, are a larger predator found throughout the lionfish’s invasive range. Because these two species use similar resources and compete for similar habitats, it is important to understand how they interact and what may result from their competition.

The invasive Pacific red lionfish, Pterois volitans. (Source: Smithsonian Marine Station at Fort Pierce)

In order to investigate how Pacific red lionfish and Nassau grouper affect each other’s behavior, the three scientists set up an experiment to compare their distance from and use of shelter when in isolation versus when both species were in the presence of each other with limited shelter. The two species were first held in separate cages with partitions to allow for isolation periods lasting 24 hours, and interaction periods lasting 48 hours, with each cage containing a shelter that the scientists constructed. The trials were based on size-ratio treatments: first they observed similarly sized lionfish and Nassau grouper, then they observed a juvenile lionfish and a substantially larger juvenile Nassau grouper, and lastly they observed an adult lionfish and a much smaller juvenile grouper. Finally, to test for predation between the two species, they incorporated a prey fish in some of the trials.

The native Nassau grouper, Epinephelus striatus. (Source: IUCN Red List)

Upon statistical analyses, Raymond, Albins and Pusack eventually came to two conclusions regarding the interactions between these two species, and specifically Nassau grouper avoidance behavior: first, they found that when Nassau grouper interacted with smaller lionfish, they avoided them by moving further from the shelter occupied by lionfish, and by using the shelter less often, and second, they found that when Nassau grouper interacted with similarly sized lionfish, they avoided them by increasing their proportion of shelter use, and by avoiding the part of the experimental cage where lionfish were consistently present. The scientists ultimately found that the Nassau grouper significantly changed position relative to shelter in the presence of lionfish, however the lionfish did not change their positioning upon interacting with the Nassau grouper. This demonstrates how they have a tendency to compete for limited shelter, and the manner in which the Nassau grouper avoid lionfish is size-dependent.

Configuration of experimental cages used in this study.

While this study highlights the competitive interactions for shelter between invasive Pacific red lionfish and Nassau grouper, it is important to note that it was performed in a laboratory setting. For future conservation efforts, it will be critical to consider how this might apply in a natural reef habitat, and whether or not this competition could lead to lionfish being a dominant predator rather than the native Nassau grouper, a shift that may result in trophic cascades.

Reference:

Raymond, WW, Albins MA, Pusack TJ. Competitive interactions for shelter between invasive Pacific red lionfish and native Nassau grouper. Environ Biol Fish (2015) 98:57-65. 31 January 2014.

Fish are Friends and Food: The rise of the US federal seafood certification

February 6, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by RJD Intern Daniela Ferraro

As appetite increases, people are looking towards federally managed fisheries to provide a seafood certification system. With rising levels of overfishing, habitat destruction, and mismanagement, there has been an emphasis placed upon fishing regulations and sustainable fishing practices (Jackson et al 2001). This began with adjustments to the Magnuson-Stevens Fisheries Conservation and Management Act (MSA) in 2006, giving the National Marine Fisheries Service (NMFS) and Regional Fishery Management Councils permission to establish annual catch limits. Fishing limits are an attempt at keeping stocks from being overfished. Sustainable fishing is the process of maintaining a balance in favor of the number of fish reproduced versus stocks fished. Unfortunately, stocks are not rebuilding and continuing to decline in number (Rothschild et al).

400 tons of Chilean jack mackerel caught in a purse seine. Photo source: Wikimedia Commons

The federal government’s jurisdiction reaches as far as the end of the Exclusive Economic Zone from 3 to 200 miles offshore. In the past 8 years, from 2007 to 2014, the federal government has worked to develop a framework for seafood import and certification as well as an eco-label program. These guidelines abide by the standards set in the MSA with input from eight of the Marine Fisheries Advisory Committee meetings (Sasser et al 2006). Currently, there are at least 200 consumer guides and 70 certifications and eco-labels that focus on wild caught fisheries and aquaculture. The largest certification program is the Marine Stewardship Council (MSC), which acts to align fisheries based on a specific set of standards that support sustainability. MSC’s guidelines take the status of the fishery, efficacy of management, and the impact to habitat into effect when assigning certifications (Christian C 2013). In developing countries, MSA has certified fishing fleets involved in fisheries improvement projects (FIPs) to encourage sustainability. While FIPs relay the means towards sustainable fishing, these fleets don’t meet MSA standards (Bush et al). Large corporations in the United States, such as McDonald’s and Walmart, along with the European Union recently agreed to buy only MSC-certified seafood (MSC 2013).

The MSC Ecolabel, Photo source: Wikimedia Commons

Opposition comes in the form of Senator Lisa Murkowski’s Responsible Seafood Certification and Labeling Act (S. 1521), a bill introduced on September 18, 2013. Murkowski proposes to prevent the federal government from granting contracts to third party certification seafood vendors, promoting a label based on criteria developed by a third party, and upholding standards that recommend third party seafood. This bill directly opposes third party seafood certifications. The National Marine Fisheries Service (NMFS) assisted MAFAC and NOAA in developing FishWatch, an agency dedicated to providing seafood consumers with information on federally managed fisheries (30). It competes with nongovernmental efforts by the Monterey Bay Aquarium and Blue Ocean Institute to “provide(s) easy-to-understand science-based facts to help consumers make smart sustainable seafood choices” (NMFS 2013). While still claiming neutrality, NMFS has taken a step towards federal certification and eco-labeling.

Fishermen in Sesimbra, Portugal. Photo source: Wikimedia Commons

In attempt to reconcile a national fishing industry and local fisherman with third party certifiers, NMFS has space to be the go-between and resolve conflict. In creating its own labeling and certification program, NMFS will serve as an advocate for fishermen in an economy that serves the consumer over seafood sustainability. The necessity and demand for a federally-managed certification program deals with issues such as market, fisheries, and communication. A reinforcing of existing structure coincides with the thought that third-party organizations and their certifications are methods of privatizing governance. MAFAC and NMFS tackle not only the definitions of sustainable fisheries but issues of control and who should have the authority to claim sustainability. In the future, fishery certification and eco-labeling could become the next wave of categorizing seafood, with “sustainable” sitting right alongside “organic” and the Organic Foods Protection Act (Stoll et al. 2014).

References

Bush S, Toonen H, Oosterveer P, Mol A. The ‘devils triangle’ of MSC certification: balancing credibility, accessibility and continuous improvement. Mar Policy 2013l 3:288-93

Christian C, et al. A review of formal objections to Marine Stewardship Council fisheries certifications. Biol Conserv 2013; 161: 10-7

Jackson J, et al. Historical overfishing and the recent collapse of coastal ecosystems. Science 2001; 293 (5530): 629-37

Marine Stewardship Council (MSC). McDonald’s first USa national restaurant chain to serve MSC certified sustainable seafood to all US locations. 2013b

National Marine Fisheries Service (NMFS). FishWatch. 2013

Rothschild B, Keiley E, Jiao Y. Failure to eliminate overfishing and attain optimum yield in the New England groundfish fishery. ICES J Mar Sci: J du Cons 2013:fst118

Sasser E, Prakash A, Cashore B, Auld G. Direct targeting as an NGO political strategy: examining private authority regimes in the forestry sector. Bus Polit 2006; 8(no. 3): 1-32

Stoll J, Johnson T. Under the banner of sustainability: The politics and prose of an emerging US federal seafood certification. Mar Pol 51 2015: 415-422

Towards more efficient longline fisheries: fish feeding behavior, bait characteristics and development.

January 26, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Sarah Hirth, RJD Intern

There has been a growing demand for bait resources seeing that standard bait types, such as squid, herring and mackerel are also used for human consumption. As a result, bait prices have increased, thus increasing the demand for an alternative bait, one that is not based on resources used for human consumption. This study highlights factors that need to be taken into consideration when looking for alternative bait, and explores attempts of alternative baits that have been made.

Løkkeborg at al. agree that an alternative bait should be “effective, species- and size-selective, practical for storage and baiting, and based on low-cost surplus products.” An alternative bait that would meet all of these characteristics would also make the procedure of longline fishing more environmentally friendly.

Although there have been several attempts to develop alternative baits, these have had limited success (e.g. Bjordal and Løkkeborg 1996; Januma et al. 2003; Polet al. 2008; Henriksen 2009). There have been two main methods, which have been used to create the alternative bait. These are natural resources, such as surplus products from the fishing industry and synthetic ingredients as attractants. Mentioned types of alternative bait are: Norbait, artificial bait invented by William E.S. Carr, bait bags, and arom bait.

When these baits were tested, they all resulted in some positive factors. However, they still had undesirable outcomes. For example Norbait, which is based on surplus products, where minced fish products are mixed with alginate (a gelling agent, used as the binder) and extruded into a fiber mesh tube, has resulted in species –selective effects. In fishing trials Norbait has resulted in increased catch rates of two to three hundred per cent for haddock, yet Norbait compared poorly to natural bait for cod. “Compared to natural bait, minced herring enclosed in a nylon bag resulted in a 58% higher catch rates for haddock, a non-significant catch increase for tusk and ling, and a considerably lower catch rate for cod.” Similar results were observed with the other types of alternative baits.

The efficiency of longline baits depends on several factors, which are important to take into consideration when finding alternative baits. Some factors include: bait size, texture, and taste. An alternative bait also needs to be based on an odor source, and attractants need to be released over a considerable period of time. Løkkeborg et al. state that “the knowledge of food search behavior in fish is the basis of bait development efforts.” The list of factors affecting feeding behavior in this review includes: temperature, feeding motivation and hunger state, diel, tidal and annual rhythms, light levels, seasonal change in photoperiod, and water currents.

Although there currently are no alternative baits used in longline fishing, Løkkeborg et al. hope that improved knowledge of how fish respond to baited gear will aid future research aimed at the development of alternative baits. As the demand for marine resources for human consumption continues to increase, costs for longline bait are also likely to keep increasing. “The development of alternative baits used on resources not used for human consumption may therefore prove to be critical to a viable longline fisheries.”

Løkkeborg, S., et al. (2014). “Towards more efficient longline fisheries: fish feeding behaviour, bait characteristics and development of alternative baits.” Reviews in Fish Biology and Fisheries 24(4): 985-1003.

“Near-future Ocean Acidification Will Require Single-Species Approach to Management”

January 23, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Stephen Cain, RJD Intern

It’s difficult to predict the effects of near-future ocean acidification (OA) across ecoregions and ocean habitat. The body of research has been conducted under a variability of circumstances and conditions. While evidence continues to mount for OA as a global mega trend, researchers like Christopher E. Cornwall and Tyler D. Eddy call for the need to contextualize OA within local coastal communities. It is there, after all, that the combined effects of pollution, resource extraction, and preservation interact within geographically distinct units. The results of multiple stressors, anthropogenic or otherwise, can alter an ecosystem’s structure and function. In their recent study, Cornwall and Eddy suggest that management regimes rely on current global predictions as well as modeling of single-species’ response to changes in ocean chemistry.

For their study, Cornwall et al. used the intertidal and subtidal habitats from the Wellington south coast, and the Taputeranga Marine Reserve off New Zealand. Both possess similar substrate and habitat, and fall within the larger Cook Strait Region. Wellington features extant commercial and recreational fisheries that primarily target Lobster (Jasus edwardsii), Abalone (Haliotis australis and Haliotis iris), as well as Blue Cod (Parapercis colias) and Butterfish (Odax pullus). According to cited work by Breen & Kim (2006), Cornwall et al. note at the time of study that Lobster abundance had been maintained at 20% of original unfished biomass. Taputeranga Marine Reserve (MR), by contrast, was established as a no-take zone at its outset in 2008.

Jasus edwardsii (http://commons.wikimedia.org/wiki/File:Jasus_edwardsii_02.JPG)

Building on a model developed by Eddy et al. (2014), Cornwall and Eddy describe the challenge of scaling down global predictions of OA to their study area. In the body of literature, the effects for net-calcification have been generated from a variety of “carbonate chemistry conditions.” The resulting baselines do not, on their own, serve as complete proxies that the research team could use to base their predictions on. They relied on calculating levels of “dissolved inorganic carbon and total alkalinity, pH on total scale, and partial pressure of CO2” in the survey area, and compared this to the predicted rise of CO2 concentrations between 2014 (380 ppm) and 2050 (550 ppm).

To measure the ecosystem dynamics they used Eco-modeling software EwE. They examined a fully factored set of scenarios comprised of four criteria: fished areas (Wellington), non-fished areas (MR), and the presence or absence of OA. In order to generate estimates for 2050, fishing mortality was held constant from 2008 biomass. The scenario for fished area with an absence of OA was used as the baseline of the study. To further delineate changes over time, four indicators of ecosystem interaction were synthesized:

Proportion of benthic biomass affected
Proportion of pelagic biomass affected
Impact by Trophic Level
Mean Trophic Level of community

After initial modeling, they noted that certain species showed dramatic changes in abundance across scenarios. Further sensitivity analyses, referred to as “blanket modifiers,” strengthened their assumptions about the changes in food web interaction and ecosystem function. One of the more noteworthy findings were the predictions of abundance for Lobster, a keystone species. Outside of the marine reserve Lobster numbers were maintained, albeit at a “fraction” of their original unfished biomass. In a scenario of MR + OA in 2050, however, Lobster abundance was reduced by 42%. This was due to heightened sensitivity to OA. As a result, researchers predicted there would be fewer predations on species at lower trophic levels, and subsequent shifts in the structure of the food web. In that same scenario, “Abalone, piscivorous fishes, and herbivorous fishes increased in biomass by 52%, 11%, and 13% respectively.”

These results may be counterintuitive because there is the expectation that protected areas better compensate for additional stressors than do areas under fishing exploitation. This is the case, and that was what the team correctly hypothesized. However, Cornwall et al. point out the nuances of near-future ocean acidification at a species-specific level. They maintain that the effects will be “subtle, species specific, and context dependent.” Apart from calcareous species, not all species stand to lose, and, in fact, some may flourish. Cornwall and Eddy suggest that these findings can be useful when comparing regions, and targeted catches of species, especially those that will face increased pressure from changes in ocean chemistry.

Challenges in seabird by-catch mitigation

January 21, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Hanover Matz, RJD Intern

In this paper, the authors comment on the current conservation status of seabirds and attempts to limit seabird deaths due to by-catch. Two species of seabirds, the albatrosses and the petrels, are particularly vulnerable to the detrimental effects of fisheries such as longlining. These birds normally lay only one egg per clutch and breed infrequently. They have long maturation and generation times compared to other birds, making it more difficult for their populations to recover from high mortality. They are also capable of flying long distances in search of food, crossing many different marine environments. This makes it difficult to implement conservation methods that can protect these birds in every part of the world they inhabit. Some of these species are already considered endangered or critically endangered. In order to fully protect them, an international effort is necessary.

A wandering albatross (Diomeda exulans) off Tasmania, Australia. Photo courtesy of JJ Harrison via Wikimedia Commons

Seabirds and human fisheries come into conflict in many of the most productive regions of the ocean, specifically around New Zealand and Australia, the Humboldt Current off Chile, Peru, and Ecuador, the North Pacific, and South Africa. Seabirds are known to be killed as accidental by-catch in longline fisheries, and growing evidence has shown incidental catch of seabirds by trawlers. One difficulty in assessing whether trawling or longlining presents a greater threat to seabirds is the low proportion of entangled seabirds actually recovered from trawling gear. If the birds that collide with the gear cannot be retrieved, it is hard to assess the impact the fishery has. Refining the collection of data on how many seabirds are killed by longlining and trawling will improve conservation efforts.

In South Africa, the use of bird-scaring lines (BSLs) in fisheries has been shown to reduce the mortality of seabirds up to 95%. The trawl fishery previously had proportionally high incidental catches of albatrosses, making this a significant success in terms of protecting threatened species. However, to fully determine how well seabird mortality has been reduced, better data needs to be collected on both the level of by-catch and fishing effort. To reduce the by-catch of seabirds and improve conservation worldwide, the authors stress four important strategies. First, mitigation methods need to be improved with better data and techniques, considering each fishery individually and adapting the methods as necessary. Second, the quality of data collected needs to be increased by improving the programs used to collect it. Third, the fishing industry needs to be engaged by implementing and enforcing by-catch reduction, as well as cooperating to suit the needs of both the fishery and conservation. Finally, cooperation between governments, administrators, and decision makers is necessary to promote better fishing practices and conservation measures. In some fisheries, seabird by-catch mitigation is minimal or nonexistent. While trawling and longlining have been addressed, the effects of purse-seine and gill net fisheries are poorly understood. The threat posed by small scale and artisanal fishing fleets has also not been widely considered. If threatened seabird species are to be protected, it will require both national and international efforts. By improving the science behind the conservation, and cooperating with both governments and fisheries, scientists and conservations will be better able to address this conservation issue in the coming future.

References

1. Favero, M., & Seco Pon, J. P. 2014. Challenges in seabird by‐catch mitigation. Animal Conservation, 17(6), 532-533.

A Century of Fish Biomass Decline in the Ocean

January 9, 2015/2 Comments/in Conservation, Ocean News /by aanstett

By Lindsay Jennings, RJD Intern

There have been many interpretations and heated debates in the scientific community surrounding the trend of global fish populations. Although some advocate increasing trends, others are quick to counter with their evidence of declining trends. And while previous local and regional studies have reported heavy declines of large oceanic predators (e.g. finish and sharks), subsequent studies have reported an increase and abundance of forage fish (e.g. anchovies and sardines). This increase in biomass is thought to be a result of decreasing predator abundance coupled with the consequences of human exploitation. Because ‘fishing down the food web’ is not a universally accepted phenomenon, and to get to the bottom of the debate, Villy Christensen et al. (2014) aimed to specifically evaluate how the biomass of high tropic level species has changed relative to the biomass of lower trophic level species.

Blacktip reef sharks scattering a school of forage fish. Photo courtesy of Wikimedia Commons

The researchers built a database with 200 data-rich ecosystem models – currently the most widely used ecosystem modeling approach in the marine environment. These models delivered ‘snapshots’ of how much life was in the ocean at a given point in time and space, between the years 1880 and 2007. From those models, Christensen et al. distributed previously-published and well-documented fish biomass based on habitat preference, ecology, and feeding conditions. With those global distributions, over 68,000 estimates of biomass were obtained for predatory or ‘table’ fish (trophic levels 3.5 and above) and forage fish (trophic levels 2.0 – 3.0). Finally, the spatial models and thousands of predictions of fish biomass were used as the basis for multiple regression analyses to predict actual trends in fish populations.

Global distribution of the ecosystem models used in this study. Color density is indicative of the number of models at each location. Photo courtesy Christensen et al. (2014)

Drawing a global picture of how the abundance of fish has changed in the world’s oceans over the last 100 years, results predicted that the biomass of predatory fish in the world’s oceans has declined by two-thirds over the last 100 years. Most alarming though is that 55% of that decline has occurred in the last 40 years. This decline in predatory fish was found to be closely linked to an increase in global fishing effort, indicating that we may have been fishing past the maximum sustainable yield (MSY) for quite some time. Consequently, forage fish biomass has increased over the last 100 years, thought to be result of predation release.

Global spatial distribution of predatory fish for (a) 1950 and (b) 2010. Photo courtesy Christensen et al. (2014)

While the researchers are confident there will be fish in our oceans in the future, they are quick to point out that those fish assemblages will be very different from the ones we have currently – with small prey fish beginning to dominate marine ecosystems. With advancing technology and increased fishing effort, this study has important implications for the management of our ocean’s marine resources. There must be a wide recognition of the growing importance of forage fish in the marine ecosystem, followed by appropriate measures to make sure these fish stocks, too, do not start to decline.

Citation: Christensen, V., Coll, M., Piroddi, C., Steenbeek, J., Buszowski, J., & Pauly, D. (2014). A century of fish biomass decline in the ocean. Marine Ecology Progress Series, 512, 155-166.

Marine Pollution: A Look into the Great Pacific Garbage Patch

January 5, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Hannah Armstrong, RJD Intern

Plastics, among other pollutants, are one of the most commonly found in oceans and on beaches globally. This is mainly for two reasons: first, plastic is very durable and often low in cost, so it is universally used for consumer and industrial products, and second, plastics do not biodegrade completely, remaining in the world’s oceans and on beaches for extended periods if not cleaned up. All of this accumulating debris can be detrimental for marine life. Seals, turtles and seabirds often get entangled and drown in abandoned fishing nets and other miscellaneous debris, and toxins both from the breakdown of plastics and those that the plastics themselves absorb, can collect in marine organisms and be damaging to their health and to the aquatic food web as a whole.

In the North Pacific Ocean, there is a gyre that has caused such a drastic collection of debris that it has earned the name The Great Pacific Garbage Patch. A gyre, as defined by the National Oceanic and Atmospheric Administration (NOAA), is a major spiral of ocean-circling currents; global winds result in ocean currents circling clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere, with an area of high pressure in the center. In the North Pacific Subtropical Gyre, these ocean circulation patterns are what caused, and is still causing, the substantial amount of debris accumulation, ultimately forming the Great Pacific Garbage Patch. The Great Pacific Garbage Patch is comprised of the Eastern Garbage Patch, which is located near Japan, and the Western Garbage Patch, which is located in the waters between California and Hawaii.

A representation of the ocean currents and zones in the North Pacific Region. The two green shaded circles depict the Western and Eastern Garbage Patches, where a substantial amount of marine debris has accumulated (Howell et al. 2012).

Charles Moore, the oceanographer who was among the first to draw media attention to the Great Pacific Garbage Patch, noted that in the last two decades alone, the deposition rate of plastic accelerated past the rate of production. Moreover, his research on plastics in the ocean showed that between 1960 and 2000, the world production of plastic resins increased 25-fold, while recovery of the material remained below 5%; and between 1970 and 2003, plastics became the fastest growing segment of the US municipal waste stream, increasing nine-fold. According to Moore, marine litter is now 60–80% plastic, reaching 90–95% in some areas (Moore 2008). This build-up is already beginning to render its consequences on the marine environment and its inhabitants.

The most obvious concern with a debris build-up caused by the previously described convergence zones is the negative effects it poses on the marine life. Specifically, this pollution affects at least 267 species worldwide, including sea turtles (86%), seabirds (44%), and marine mammal species (43%) (Laist 1997). In 2009, Young et. al directed their attention toward an area southeast of the Kroshio Extension near Japan. They observed a population of Laysan Albatross (Phoebastria immutabilis), taking note that the foraging area of adult albatross originating from Kure Atoll overlapped with the range of the Western Garbage Patch. This, they realized, is what lead to the transfer of marine plastics from adult albatross to their young. In fact, the albatross chicks from Kure Atoll, in comparison to the Oahu albatross sample used, were fed nearly ten times the amount of plastic despite having a relatively similar amount of available natural food. While Young et al. were unable to determine the level of mortality as a result of this plastic ingestion, they did observe mechanical blockage of the digestive tract, reduced food consumption, satiation of hunger, and potential exposure to toxic compounds (Young et al. 2008).

A photograph of a dead Laysan albatross chick with a diversity of plastics in its stomach. Ingestion of marine debris is a detrimental issue or marine organisms and seabirds (Young et al. 2008).

In addition to threats of ingesting pollutants, marine species face threats of entanglement and a phenomenon known as “ghost fishing.” This occurs when fishing gear is lost or abandoned, but continues to fish and wipeout resources (Moore 2008). As a means of remediating entanglement, often a result of nets and six-pack soda rings among other pollutants, some manufacturers aim to chemically alter the plastic in the event that it ends up in the ocean. Chemical changes can allow the polymer to absorb UV-B radiation from sunlight, breaking it down into a smaller, less-harmful product. The resulting polymer, however, is hardly more biodegradable (Moore 2008).

With the ever-increasing abundance of plastics in the marine environment, concerns too, are growing. With other environmental problems, most notably climate change, it will be critical to begin (and continue) to study and understand how rising atmospheric and sea temperatures will affect ocean circulation, wind and debris movement patterns. If drastic changes occur within the North Pacific region, and specifically the area encompassed by the Great Pacific Garbage Patch, then the resulting marine pollution accumulation and retention and could be drastic as well.

References:

Derraik, Jose G.B. The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin 44 [842-852]. 2002.

Howell, Evan A et al. On North Pacific circulation and associated marine debris concentration. Marine Pollution Bulletin 65-1 [16-22]. 2012.

Moore, Charles James. Synthetic polymers in the marine environment: A rapidly increasing, long-term threat. Environmental Research 108-2 [131-139]. 2008.

Young, Lindsay C et al. Bring Home the Trash: Do Colony-Based Differences in Foraging Distribution lead to Increased Plastic Ingestion in Laysan Albatrosses? Plos One. 2009.

14 things our lab accomplished in 2014

December 30, 2014/0 Comments/in Conservation, Ocean News /by aanstett

1) We published “Evolved for extinction: the cost and conservation implications of specialization in hammerhead sharks,” a review of hammerhead biology and conservation that was featured on the cover of BioScience! Read it here:

2) We led 65 shark research trips, including two trips to our Tiger Beach research site in the Bahamas!

3) We published “Considering the fate of electronic tags: interactions with stakeholders and user responsibility when encountering tagged aquatic animals,” which was featured on the cover of “Methods in Ecology and Evolution.” Read it here:

4) We brought over 1,200 citizen scientists out on the research vessel with us to learn about sharks, participate in our scientific research, and learn about local conservation issues. They ranged in age from 10 to 73, came from 46 states and 40 countries, and included representatives from 33 schools, community organizations and corporations.

5) We published “an assessment of the scale, practices, and conservation implications of Florida’s charterboat based recreational shark fishery,” which was featured on the cover of Fisheries. Read it here

6) We caught, measured, sampled and tagged 331 sharks of 11 species. The most common species we caught was the nurse shark (151 individuals). We also caught 6 Atlantic sharpnose, 25 blacknose, 15 blacktips, 15 bulls, 10 Caribbean reefs, 19 great hammerheads, 26 lemon sharks, 27 sandbar sharks, 1 scalloped hammerhead and 36 tiger sharks.

7) We published “Physiological stress response, reflex impairment, and survival of five sympatric shark species following experimental capture and release,” an important paper showing how the stress of being caught by fishing gear can harm or kill a shark even if it is eventually released. Read it here

8 ) We attached satellite tags to 19 sharks: 8 great hammerheads, 1 scalloped hammerhead, and 10 tiger sharks. You can track all of our satellite tagged sharks here using Google Earth, and you can adopt your own, name it, and join us when we tag it here

9) We published “Vulnerability of oceanic sharks as pelagic longline bycatch,” an analysis of how different species of sharks react to being caught as bycatch in commercial fisheries. Read it here.

10) Our students presented their research at major scientific conferences, including Sharks International, the American Elasmobranch Society meeting, and the International Marine Conservation Congress!

11) We published three papers from our morphometric analysis project! Read them here: 1, 2, and 3.

12) Our research was covered in many media outlets, including Al Jazeera America, the South Florida Sun-Sentinel, and CBS News!

13) Our interns wrote dozens of blog posts on a huge variety of topics related to ocean science and conservation.

14) We passed 4,000 fans on our Facebook page, which continues to share ocean science and conservation news! Have you “Liked” our page?

Thanks for your continued support! With your help, 2015 will be even better!