Finding “The Lost Year” Sea Turtles: The potential threats and conservation implications

by Ashley Hill,
Marine conservation student

Open ocean habitats are innately difficult to access. As a result, the majority of research on sea turtles is restricted to beach and coastal areas. However, there is a time span of several years from when hatchlings venture offshore to when the larger, juvenile turtles return to coastal waters. It is thought individuals of this life stage must live in the open ocean, but the lack of concrete, direct evidence has led to the term “the lost years” (Carr et al. 1978). The majority of the open ocean is desert like, with vast areas of minimal amounts of food or shelter. Oceanic processes push water together to form areas of convergence. These areas typically contain higher levels of plankton and therefore a higher abundance of other organisms that take advantage of the increased food source. In the Atlantic, Caribbean and Gulf of Mexico, convergence areas are often traced by lines of a branching, floating alga called Sargassum (Thiel and Gutow 2005, Butler et al 1983). Each individual clump of Sargassum is less than 80cm, but mats spanning hundreds of meters wide and tens of thousands of meters long can be formed in convergence areas (Butler et al 1983). In a way, these Sargassum drift communities can provide an oasis of nourishment and shelter for an assortment of organisms, including sea turtles.

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Black Reefs Threaten Coral Diversity in the Line Islands

By Candice Canady,
Marine conservation student

Coral reefs are threatened globally and, without an undisturbed example from which to form a baseline, researchers are hard-pressed to predict how global and local stressors influence them. Luckily, a number of coral reefs exist in the Central and South Pacific that may hold the key to better understanding changes in reef populations worldwide. The Line Islands, located south of Hawaii, are home to some of the most pristine reefs in the world (Knowlton and Jackson 2008). These reefs have high biodiversity and have experienced very little influence from human populations (Barott 2013). However, they are threatened by their own unique set of stressors. The Central Pacific is traditionally an iron-poor region. This lack of iron reduces competition between coral and primary producers, such as algae and cyanobacteria (Martin and Fitzwater 1988). Recent studies have noted phase shifts (shifts from coral-dominated structures to regions dominated by algae) on coral reef atolls throughout the Pacific as a result of iron pollution (Kelly et al. 2012). These areas have been termed “black reefs” due to the dark-colored turf algae that covers the bottom (Barott 2013). A 2012 study by Kelly et al. showed that the black reefs in this area were introduced by shipwrecks that serve as point sources of iron pollution, causing algal and bacterial blooms that kill the natural coral reef structure.

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Treatment of Invasive Aquatic Species Found in Ballast Water

By Abbigail Rigdon,
Marine conservation student

As the world becomes more globalized, countries that at one time seemed distant are now easily traveled and easily contacted. Such contact does not exist only between humans, but between other species as well. Sometimes, however, these species can be detrimental to their new environment. Foreign species may be introduced to new environments accidentally (by releasing an exotic pet into the wild, for example), or purposefully (in order to manage an overabundance of a native species by increasing its competition, or by increasing the amount of predators for the species). One major method of accidental introduction is through the release of ballast water from ships.
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Sea Ranching: More Economically Feasible then Other Harvesting Techniques?

By Samantha Feingold,
Marine conservation student

Atlantic Cod fish (Gadus Morhua). A common commercial species. This study investigated the economic feasibility of various harvesting practices. (NOAA, 2010)

Atlantic Cod fish (Gadus Morhua). A common commercial species. This study investigated the economic feasibility of various harvesting practices. (NOAA, 2010)

In Need of Protein!

            Fifty or sixty years ago, fishermen’s catches were much more diverse and productive. Routinely fishermen returned to their slips to show off several tuna and grouper, sizing longer then the workers were tall. Looking back at old photographs of a daily catch, one would think the fish were prehistoric or from a science fiction movie. It was fabled that colonists of New England appeared to walk over water via the backs of codfish or lobsters. Today, catches have significantly downsized; the fish are much smaller and the catches are less diverse. As a result, fishermen are being forced out of the industry or otherwise seeing a smaller profit.  Meyers and Worm (2003), prominent marine biologists, have reported that 90% of large predatory marine fish in several areas have been depleted–and most fishermen would agree. Meanwhile, human population continues to rise. Today global population is 6.9 billion. If the growth rate stays constant, it is projected that by 2050 global population will reach 9.3 billion people (the difference being the current population of China and India combined; UN 2011). In 2009, fish consumption was 12.4 percent of total animal protein globally (24% in low income food deficit countries; FAO 2012). As human population rises and fisheries continue to decline, a global crisis for fish protein is escalating. The advancement of fishing technology, poor fisheries management, and growing population, are combining to create a global demand for aquaculture.

Aquaculture: A Diverse Industry

            The urgency of aquaculture innovation is relatively recent, but the industry is beginning to see a boom, especially in South America and Asia. Aquaculture is the umbrella term for fish farming and is most commonly visualized as growing fish in ponds, tanks and offshore cages. It is often understood as producing fish from eggs, growing them to marketable size, and breeding them to produce viable eggs, which is called full-cycle aquaculture. Within full-cycle aquaculture, the spectrum of diversity of systems is wide, yet there is a great need for advancement. But other than full-cycle aquaculture, newer, less recognized forms of aquaculture exist: for example, sea ranching.


The Study

In a recent study by Halldórsson, et al. (2012) the authors investigate a type of aquaculture termed ranching, whereby fish are attracted in their natural environment to a certain location repeatedly and then ranchers harvest them as a group once they have reached a marketable size. This does not involve caging the fish. This practice is also commonly referred to as herding or aggregating fish. Most ranching practices utilize feed to attract the fish, although there are recent studies trialing the use of acoustics as the attractant. This type of ranching differs from the practice of on-growing, whereby fishes are captured as juveniles, then fattened up in offshore cages before finally harvesting them for market. Halldórsson et al. suggest that sea ranching can be more economically feasible than full-cycle aquaculture, traditional fishing and on-growing. I will consider this thesis.


Halldórsson, et al. compared production of coastal cod (Gadus morhua) in Iceland. The study examines which practice would be most profitable for an existing fishing company with a 200 ton cod quota, fishing permit and 30 ton boat: continue to fish, ranch, on-grow, or develop a full-cycle aquaculture system. For each of the practices the authors studied various inputs and outputs to estimate the overall net profit and thus economic feasibility of the practice within a fifteen year operating period. To investigate the profitability of ranching, Halldórsson and his team analyzed the work of a particular ranching business that trained the fish to eat at feeding bags that were anchored to the ocean floor. The fish were harvested using a large net that collected them at their feeding stations and then unloaded onto a boat. For fishing, full-cycle aquaculture and on-growing, the authors used data from past studies, supplemented by knowledge from other scientists, aquauculturists and fishermen.


The results showed that ranching was the most profitable, followed by fishing, and then on-growing. Full-cycle cod farming proved not to be profitable and was predicted to remain unprofitable due to high feed costs, the low market price of cod, as well as a relatively high feed conversion ratio (i.e., the ratio of mass of feed to mass of fish produced).

In addition to economical benefits, the authors argue that ranching is advantageous because it does not reduce conventional fishing practices, and will produce a greater yield for human consumption. The authors further argue that ranching reduces the negative impact on the fisheries by minimizing the catch of undersized fish and bycatch (the accidental catch) because of their acquisition strategy. The fish are trained to aggregate at the feeding stations, which makes targeting them easy and avoids the use of harmful fishing techniques.

Analysis of Study

The results of the study are not surprising. Ranching requires fewer inputs than any of the other practices which make it more economical within the analyzed time period. Because the fish roam their natural environment the feed costs are much less then on-growing and full-cycle fish farming. The study estimates that half the feed for ranching and on-growing is wild fish that the cod prey on outside the feeding stations. Feed is often the most costly budget item for aquaculture farms. Therefore, halving the feed reduces the company’s overall expenses significantly.

Cod fishing was concluded to be the second most profitable practice. This might be true if we disregard that cod populations are in decline. Although cod populations in Iceland are healthier than they are in the Western Atlantic, the fishery is most likely not sustainable. Árnason et al. (2009) predict that the Icelandic cod fishery will collapse like the Eastern Cod fishery due to persistent fishing pressure energized by growing demand. As cod continues to be overfished, the cod fishery will become less and less feasible. The Halldórsson, et al. paper does briefly acknowledge this. Its purpose is not to encourage fishing, but instead scale the economic feasibility of the various practices relative to traditional cod fishing; fishing being the baseline to which the other practices are compared. Its analysis does not however, calculate the economic or practical probabilities of the declining cod fishery.

On-growing was proven to be unprofitable, which is emphasized by the closure of several on-growing businesses in Iceland. The study neglects to address a negative factor of on-growing which is harvesting the fish when they are likely sexual immature preventing the fish from reproducing. This practice can be argued is worse than traditional fishing because it prevents the success of the future generations.

It should be mentioned that ranching and on-growing are just different ways of harvesting from the open ocean. One important advantage of these two practices over fishing is they return a greater yield because feeding them consistent, nutritious food before harvesting them increases their biomass. Ranching and on-growing does not decrease the pressure on wild cod populations in any known manner.

In the study, full-cycle cod farming saw no profit in the fifteen year timeframe. The concept of full-cycle aquaculture is to efficiently create an environment that mimics the species’ natural environment in order to grow healthy fish, which is a very costly task. In order to earn a profit, it must be large scale, have very significant initial funding and be prepared to operate for years before making a profit. Full-cycle farms are a bigger investment that a 30-ton boat, quota and fishing permit. The practice is currently still developing and evolving, with various inefficiencies to resolve.

The study makes the logical conclusion that full-cycle fish aquaculture is less economically feasible then the other practices. This should not be understood as saying that full-cycle aquaculture will never be profitable given sufficient capital and time. The study was intended to show fishermen who are trying to evaluate their alternatives, which of the different practices is most practical.
Positive Future for Ranching?

Although at first glance the paper might seem skewed (or uneducated regarding full-cycle aquaculture), its purpose as a tool for current cod fishermen is useful. Sea ranching is an interesting concept. It could be a beneficial investment for a fisherman who is looking to get out of conventional fishing. There are issues that must be investigated further, however, including the fidelity of the fish. What if the fish migrate? The study stated that if the ranchers do not harvest 75% of the conditioned cod or more, the economical feasibility would not be viable. Also, what prevents other fish from being attracted to the feed bags? In that case, the ranchers are not only feeding undesired fish costly feed, but they will catch them (an important conservation concern). Lastly, there is a lack of permitting available for these ranchers. Local or commercial fishermen could easily take advantage of the aggregated fish in the area unless they are protected somehow. These are speed bumps that probably could be resolved. Ranching could be beneficial if healthy fish populations are targeted. Ranching, as the authors defined it, may be an effective approach to lessen the negative impact that overfishing has on fishermen and the fishing industry. It is not a large step away from traditional fishing practices, but could have a positive impact on the cod fishing industry (fishermen, processors, buyers and sellers, etc). This is not the solution to declining cod fisheries, but a compelling concept that could be utilized in the meantime.


Halldórsson, JE., Björnsson B, Gunnlaugsson SB (2012) Feasibility of ranching coastal cod (Gadus morhua) compared with on-growing, full-cycle farming and fishing. Mar Policy 36: 11-17. doi:10.1016/j.marpol.2011.03.001

Arnason, Einar. Intense habitat-specific fisheries-induced selection at the molecular Pan I locus predicts imminent collapse of a major cod fishery PLoS ONE. 4: 1-14 DOI: 10.1371/journal.pone.0005529. (accessed 26 Oct 2012).

Food and Agriculture Organization (FAO) (2012) (accessed 1 October 2012)

Myers, RA, Worm B (2003) Rapid worldwide depletion of predatory fish communities. Nature 423: 280-283 (accessed 1 October 2012)

United Nations (UN). World Population Prospects: the 2010 Revision: Highlights and Advanced Tables (2011) In: United Nations Department of Social and Economic Affairs/Population Division. United Nations, New York City, p 1-142 (accessed 1 Oct 2012)


Development of Mangrove Islands within the Belize Barrier Reef Reserve System

By Christine Borski,
Marine conservation student

The Belize barrier reef and the adjacent submarine shelf make up the world’s second largest reef system and the largest in the northern hemisphere.  The Pelican Cayes group (Figure 1) is part of the South Water Caye Marine Reserve (SWCMR), an 117,878 acre marine protected area (MPA) and one of seven sites comprising the UNESCO Belize Barrier Reef Reserve System, a World Heritage Site since 1996 (,

Figure 1 from Macintyre et al. 2009

Figure 1 from Macintyre et al. 2009


It is an oceanic coral reef boundary environment with deep (10-12m) lagoon-like semi or fully enclosed intertidal ponds encircled by steep coral ridges (Macintyre et al. 2000a).  Red mangrove (Rhizophora mangle) communities have formed on these steep ridges, creating prop root substrate upon which rich communities have formed (Macintyre and Rützler 2000). The surrounding mangroves and coral ridges protect the ponds from prevailing winds and create a nutrient-enriched environment in which dinoflagellate phytoplankton populations can proliferate.  These dinoflagellates are the primary food source of zooplankton, which includes fish larvae and juvenile fish.

At the time of its inscription, the World Heritage Committee and the Government of Belize recognized that SWCMR would be protected from development except for cayes with pre-existing leases and those that were privately owned. This exception would only apply within the Pelican Cayes to a small area less than one hectare at the southern tip of Northeast Caye.

Despite this recognition of protection, most of the SWCMR cayes have been leased for proposed resort developments since 1996, and large mangrove areas in the Pelican Range have been cut down and then covered with dredged marine sediment.   The water in the sediment causes the fine particles to wash off into the pond and surrounding waters, creating high turbidity.  The purpose of clearing and covering these coral islands with white sand is to ready them for development for the leisure and tourism markets.

In order to determine the amount of change in the Pelican Cayes since 1996, Macintyre et al. (2009) compiled field observational data, aerial photographs from both pre- and post-clearing efforts, and compared studies of dinoflagellate assemblages from within the Pelican range.

In March 2007, Macintyre et al. (2009) observed in Pond C of Manatee Caye areas of dead mangrove roots and a thick layer of sediment along the sides and bottom, burying the turtle grass (Thalassia) bottom communities.  The organisms usually found living on mangrove roots in this area were absent.  The pond was fringed with dead red mangroves.  The land behind was recently cleared and covered with white marine sediment.  The dredging work on Manatee Caye had finished at this time, although work on Fisherman’s Caye appeared to be underway since clear-cutting, large-diameter pipes, and a dredging vessel anchored off-shore of the island were seen.

From a series of aerial photographs taken since 2003, of all the cayes in the area, only Northeast Caye had shown signs of development prior to March 2003.  By April 2006, all but one of the Bird Cayes had begun to be cleared.   Areas of high turbidity along the edges of the ponds and outer shores of the mangrove islands were visible from the air.

Macintyre et al. (2009) also noted wide-spread cleared and filled areas on both Manatee and Fisherman’s Cayes, survey lines indicating more development, and an area of bare seabed near Manatee Caye signifying the location of the dredge operation (Figure 2).  Of the 53.3 hectare area in the Pelican Cayes, 29% (15.4 ha) had already experienced clearing, burning and filling of the mangrove forests.

Macintyre et al. (2009) compared the diversity of dinoflagellate populations along the north side of Pond C to that found by Faust (2000) in the same location before clearing in May 1996. They found fewer live dinoflagellate cells than expected, with a 77.3% decrease in total species.

These declines in the physical and biological health of the Pelican Cayes are one example of a widespread problem.  World-wide, mangroves are threatened with clearance for tourism, agriculture, urban development, aquaculture and resource exploitation (Alongi 2002, Giri et al. 2008).  From 1950 to 2000, over 50% of the world’s mangroves have been lost with at least 35% from 1980 to 2000 (Viliela et al. 2001, MA 2005).  At the current rate, mangroves are expected to be extinct in 100 years and with them, all the unique and important ecosystem goods and services they provide (e.g. biodiversity, filtration, carbon sequestration, nursery habitat, natural barrier) (Duke et al. 2007).

In 2000, mangroves were found to cover an area totaling 137,760 km2 in 118 different countries and territories, with approximately 75% found in just 15 countries (Giri et al. 2011).  With the majority of the world’s mangroves under governmental control of just 15 countries, conservation measures by these governments must be effective in order to ensure the continued sustainable existence of what is left of the world’s mangroves.

How does this happen in an area supposedly protected as a marine reserve?  According to Macintyre et al. (2009), most of the cayes within the Belize Barrier Reef World Heritage Site and the SWCMR have been leased or sold to foreign developers since 1996 simply by following standard procedures.  Multiple permits are required before each stage of development can commence, and ignorance or misunderstanding of the protections afforded to MPAs could have occurred during any stage.

In 2008, the Forest Department of Belize issued a temporary moratorium on mangrove clearing in order to review these problems (  The unique and biologically diverse ecosystems on the mangrove roots and the lagoon bottom of the Pelican Cayes ponds could be lost as a result of sediment suffocation.  Additionally, the dredging efforts stir up clouds of bottom sediment which can travel via currents to nearby islands and reefs and cause smothering there.  This sediment fill dredged from the adjacent sea floor can not only directly destroy corals and seagrasses by blocking sun light, but causes high turbidity, increases nutrient levels and releases contaminants.  After development, untreated sewage and inadequately disposed solid waste can run off into the surrounding waterways and decreases overall water quality.

Besides the ecological threats, development on these in-filled islands may not be a good idea anyway.  Subsidence due to rotting peat and the settling of the fill material, as well as the impacts from severe storms, could destroy any buildings on these islands and cause them to be abandoned.  Construction efforts and habitation will also ensure perpetual pollution of the ponds from solid waste, sediment and sewage runoff, as well as contribute to the high turbidity of waters in adjacent marine communities.   The beauty and high biodiversity of the mangrove islands and adjacent coral reefs is what enticed development in the first place.  If these communities are destroyed, there will be no reason for continued habitation and development.

Altering mangrove ecosystems for residential, tourism and commercial markets adversely affects not just the health of coral reefs but also the biomass and viability of commercial fishes inhabiting the reefs, which are vital for both tourism and local livelihoods.  The short term economic gains would not outweigh the long term losses.  Adequate protection, management and enforcement of regulations governing these mangroves islands need to be re-evaluated and re-vamped.  Potential developments on these sensitive ecosystems need to be properly managed for sustainable and low-impact practices.


Alongi DM (2002) Present state and future of the world’s mangrove forests. Environ Conserv 29:331-349

Duke NC, Meynecke JO, Dittmann S, Ellison AM, Anger K,  Berger U, Cannicci S, Diele K, Ewel KC, Field CD, Koedam N, Lee SY, Marchand C, Nordhaus I, Dahdouh-Guebas F (2007) A world without mangroves. Science 317:41-42

Giri C, Zhu Z, Tieszen LL, Singh A, Gillette S, Kelmelis JA (2008) Mangrove forest distributions and dynamics (1975-2005) of the tsunami-affected region of Asia. J Biogeogr 35:519-528

Giri  C, Ochieng E, Tieszen LL, Zhu Z, Singh A, Loveland T, Masek J, Duke N (2011) Status and distribution of mangrove forests of the world using earth observation satellite data. Global Ecol Biogeogr, 20:154-159

Faust MA (2000) Dinoflagellate Associations in a coral-reef mangrove ecosystem: Pelican and associated cays, Belize. In: Macintyre IG, Rützler K (ed) Natural history of the Pelican Cays, Belize, pp. 133-150. Atoll Res Bull, No. 473

The Forest Department of Belize: Ministry of Natural Resources and the Environment. (accessed 3 Oct 2012)

MA (Millennium Ecosystem Assessment) (2005) Mille ecosystems and human well-being: synthesis. Island Press, Washington, DC

Macintyre IG, Goodbody I, Rützler K, Littler DS, Littler MM (2000a) A general biological and geological survey of the rims of ponds in the major mangrove islands of the Pelican Cays, Belize. In: Macintyre IG, Rützler K (ed) Natural history of the Pelican Cays, Belize, pp. 133-150. Atoll Res Bull, No. 430

Macintyre IG, Toscano MA, Feller IC, Faust MA (2009) Decimating mangrove forests for commercial development in the Pelican Cays, Belize: long-term ecological loss for short-term gain? Smithson Contrib Mar Sci, 38:281-290

Macintyre IG, Rützler K (eds) (2000) Natural history of the Pelican Cays, Belize. Atoll Res Bull, Nos. 466-480

South Water Caye Marine Reserve. (accessed 23 Sept 2012)

UNESCO World Heritage Centre: Belize Barrier Reef Reserve System. (accessed 26 Sept 2012)

Valiela I, Bowen JL, York JK (2001) Mangrove forests: one of the world’s threatened major tropical environments. BioScience, 51:807-815

Blue Whiting: A New Approach to Management

by Zack Good,
Marine conservation student, RJD Intern

The blue whiting (Micromesistius poutassu) is a medium-sized fish distributed throughout the northeastern Atlantic Ocean (Figure 1).  It feeds mostly on zooplankton and smaller fish and also serves as prey for larger fish.  As far as humans are concerned, it is a significant source of both income and food.  It is important that this fishery be studied, as it is currently overexploited, much like the 88% of European fish stocks fished beyond maximum sustainable yield (Commission of the European Communities).

Sebastián Villasante studied the blue whiting fishery in Spain in his 2012 paper, concentrating on Galicia, Spain, to assess the state of the fishery from both a biological/ecological perspective and a human perspective.  By synthesizing these two perspectives he is able to look at the fishery in a different way than previous fisheries management regimes have.  Villasante even provides recommendations for management changes in the future.

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Sea Otters: A Dwindling Species that Helps to Diminish Our Carbon Footprint

By Alex Babcock,
Marine conservation student

Sea otters are recognized most for their cute appearance and adorable behaviors; however, this species also serves very important roles in its’ ecosystem. A new study, published in this month’s issue of Frontiers in Ecology and Environment, posits the importance of sea otters and carbon sequestration (Wilmers et al. 2012). We know the ocean is one of our biggest carbon sinks and that sea otters are a keystone species for kelp forest environments (Estes et al. 1978). This study goes one step further: it demonstrates that sea otters, by keeping kelp-grazing sea urchin populations low, can cause kelp ecosystems to have higher net primary productivity (NPP) and higher biomass than kelp ecosystems without sea otters present. In effect, the presence of sea otters causes more CO2 to be absorbed from the atmosphere  (Wilmers et al. 2012).

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Improving Marine Reserves

By Mary Trainor,
Marine conservation student

It is a wonderful sign of the times that governments around the world are taking action to protect the ocean.  One popular marine management tool is the marine protected area (MPA), which aims to conserve marine life and habitats by restricting what people can do within designated MPA boundaries (National Ocean Service 2012b).  There have recently been advancements in both the placement and abundance of state government regulated MPAs in United States waters.  For instance, in June of 2012,  the California Fish and Game Commission approved plans to implement the final 19 MPAs needed to complete the open-coast section of California’s Marine Life Protection Act, boosting California’s total MPA count to 119 (California Dept. of Fish and Game 2012).  In addition, the Florida Keys National Marine Sanctuary Advisory Council is currently re-evaluating the sanctuary’s boundaries and regulations in order to reflect changes in laws and scientific literature (National Ocean Service 2012a).

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Do birds of a feather forage together?

By Asta Mail,
Marine conservation student

Imagine that you are entrusted with the duty of conserving a colony of beautiful seabirds. Your objective is to create Marine Protected Areas (MPA’s) that shelter birds from disturbances, so that they can do what they do best: eat, sleep, fly and reproduce!  How then do you decide which marine areas are the most important to protect?

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Can MPAs help tropical sharks?

By Christina Marmet,
Marine conservation student

Sharks have been around for 450 million years, and have survived every extinction episode that our Earth has known since then (Litman 1996). However, human beings may be the biggest threat they have ever faced.

Today, there are about 500 species of sharks in the ocean, with more being discovered regularly. However, according to the IUCN Red List, more than one-third of all oceanic shark species are at risk of extinction. They are endangered mostly because of overfishing and the increased loss and degradation of coastal habitats (Stevens et al. 2000, Ferretti et al. 2010).

One of many possible solutions to help protect sharks is to create marine protected areas (MPAs), especially in coastal areas where sharks are most vulnerable to human impacts. However, in most cases, lack of knowledge regarding the movement patterns of sharks hinders the establishment of specific shark protected areas.

The National Oceanic and Atmospheric Administration MPA Center defines marine protected areas as “any area of the marine environment that has been reserved by federal, state, territorial, tribal, or local laws or regulations to provide lasting protection for part or all of the natural and cultural resources therein” (NOAA MPA Center accessed Nov. 1, 2012).

Hypothetical example of a marine protected area, a marine reserve, and a no-take marine reserve. Source: Pacific Fishery Management Council (

Hypothetical example of a marine protected area, a marine reserve, and a no-take marine reserve. Source: Pacific Fishery Management Council (


MPAs are put in place mostly for the protection and conservation of rare and endangered marine species and habitats, as well as to maintain the biodiversity of a specific area (Agardy 1997). MPAs can also help preserve the socio-economic value of a marine area for human use through fisheries or recreation. They are thought to be most effective at protecting sedentary species – animals who have very little movement or are attached to something – as most MPAs are small in size, and the benefits from the protection diminishes once individuals move outside the boundaries (Bonfil 1999).

Many MPAs have been put in place without prior knowledge of how they will function due to the urgent need for protection of marine environments (Roberts, 2000). In Knip et al. (2012), the aim of the study was to evaluate the possible degree to which existing MPAs may shelter shark populations by tracking the movements of two tropical coastal species within two MPA regions in the Great Barrier Reef Marine Park, Australia. Their hypothesis was that coastal sharks received conservation benefits from the MPAs by staying inside the boundaries (Knip et al. 2012).
The research was conducted from 2009 to 2010 in Cleveland Bay, within which there are two Conservation Park (CP) zones with strict fishing restrictions (Knip et al. 2012). During the course of the study, 37 pigeye sharks (Carcharhinus amboinensis) and 20 spottail sharks (Carcharhinus sorrah) were fitted with acoustic transmitters. Receivers were deployed throughout the two CP zones to monitor shark movement and residency inside the MPA (Knip et al 2012).

Acoustic transmitters allow scientists to know the location of tagged animals and time at which they pass within the range of the receivers (Welch 2005). Downloading of receiver data occurred every 6-8 weeks (Knip et al. 2012). The acoustic receivers were placed only inside the CP zones. Consequently, the interval between all detections was calculated for each individual shark to determine the length of time outside the protected area. The scientists concluded that the longer the interval between detections, the more likely the shark had exited the MPA (Knip et al. 2012).
The acoustic tagging led to the findings that pigeye sharks spent a mean of 23% of their time inside the MPA, while spottail spent a mean of 32% (Knip et. Al 2012). They also discovered seasonal variations: pigeye sharks spent twice as long in the MPAs in summer than winter, and the opposite pattern was apparent among spottail sharks (Knip et al. 2012). All individuals made excursions outside of MPAs, but the number and duration of the excursions varied among individuals of both species (Knip et al. 2012).
The authors recognized that these results lead us to believe that these two species of sharks are beneficiaries of the marine protected areas. It undeniably shows a certain degree of protection for the sharks, as they were found spending a noteworthy amount of time in the MPAs. However, the percentages also show that the sharks are out of the reserve 70 to 80% of the time, suggesting that MPAs in this region provide only limited protections for these two species, and potentially for all mobile species.
Indeed, the authors suggested that the degree of MPA effectiveness would in part depend on the seasonality of the nearby fishery industry, with respect to the seasonality and timing of excursions of sharks from MPAs (Knip et al. 2012). It would have been interesting to look at precise bycatch data, such as how many fishermen incidentally catch and release sharks, and where and when exactly they catch them. The authors mention that the location where the sharks exit the MPAs is of critical importance for conservation. Most fishing effort in this region occurs in the intertidal zone, which is where the pigeye sharks prefer to cross out of the CP zones (Knip et al. 2012). The effects of fishing pressure were obvious: fishers in this region removed 21% of the pigeye shark population, while there was no capture of spottail sharks (Knip et al. 2012), thus suggesting the need for fisheries regulations in and around the MPAs. Unfortunately, there was no discussion of fishermen sample size, and it is thus hard to determine the significance of this catch, which may represent only a fraction of total fishing threat.
This paper demonstrates the importance of knowing the movement patterns of sharks and other mobile species in order to create better conservation areas. Undeniably, it would be worth spending more time looking at the reasons for the crossing patterns in and out of the MPAs for these two species of sharks. Besides, if the area adjacent to an MPA boundary is heavily fished, the risk of capture for an individual will remain high even if it spends most of its time inside the MPA (Knip et al. 2012).
This study was among the first to evaluate the efficacy of MPAs for shark conservation (Knip et al. 2012). Consequently, it proved that not only the creation of MPAs could be an important contributor to shark conservation, but also that better knowledge of shark behavior would most likely encourage the development of more specific and effective fisheries-management plans. The authors suggest an ‘onion-ring’ type approach to MPA design, where core areas would be buffered by outer zones that exclude potentially high impact fisheries (Knip et al. 2012). It can be concluded that the effectiveness of MPAs for sharks is dramatically decreased by certain fishing activities nearby, and that there is a need for better MPA regulations in and around protected areas.
The authors came to the conclusion that this study demonstrated that individual MPAs may generate benefits for multiple shark species, and thus did not need to follow a species specific initiative (Knip et al. 2012). Although this study demonstrates that MPAs are a good first step to protecting even highly mobile species, it is crucial to remember the great diversity of shark species. These findings can really only be generalized to other shark species with similar life history and behavioral characteristics. Consequently, more research into the potential for MPAs to contribute to shark conservation is needed in different ecosystems worldwide.


Agardy, T.S. (1997) Marine Protected Areas and Ocean Conservation. Academic Press, San Diego.
Ferretti, F., Worm, B., Britten, G.L., Heithaus M.R. & Lotze H.K. (2010) Patterns and ecosystem consequences of shark declines in the ocean. Ecology Letters, 13, 1055-1071
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