Tropical Fisheries Biology

Tropical Fisheries Biology --Take Home Examination

(1) Do no-take marine reserves spillover? Give an overview of this, using examples.


One of the most key issues of Marine Reserves is the so-called “Spillover Effect”, by which described to improve biomass and diversity within the reserves enhances close to fisheries and ecosystems. Roberts et al. (1997) has been noted and studied this issue for over a decade. In particular, he noted that the dispersal of pelagic larvae from marine protected areas enhanced the productivity of “downstream” regions and made them more resilient to change. There are a number of documented examples of spillover benefits from all over the world, ranging from the unfished area off Cape Canaveral in Florida (Johnson, Funicelli, and Bohnsack 1999) to the Apo Island in the Philippines (Russ, Alcala, and Maypa 2003), and off the coasts of Kenya and Tanzania (McClanahan, Verheij, and Maina 2006).

A paper published in Science magazine on November 30, 2001 say that two sites have studied show the spillover effect is real, and that reserves can play a key role in supporting fisheries. The two reserves are the Soufriere Marine Management Area (SMMA) on the Caribbean Island and the Merritt Island National Wildlife Refuge (MINWR) at Cape Canaveral, Florida. The SMMA was designated in 1995 to rehabilitate the local reef fishery, including a network of five no-take areas. The no-take areas constitute 35% of the previous local fishing grounds. From 1995 to 1998, according to the Science paper, fish biomass in the no-take zones tripled while biomass in the adjacent fished areas doubled. Similarly, the MINWR includes two areas of estuarine habitat that have been closed to public access and all fishing since 1962, for security of an adjacent rocket launch site. In recent years, the adjacent fished areas have become a hot spot for catches of record-sized game fish, particularly red drum, black drum, and spotted seatrout. World- and state-record catches of these three species have been concentrated in the authors' study area, which extends roughly 100 km north and 100 km south of the no-take zones.

Although the evidence of long-term benefits of spillover is limited, such evidence has been increasing and has become available (Abesamis et al. 2006). Abesamis et al. (2006) studied on abundance gradients of fish across the boundaries of protected areas close to two small Philippine Islands. The finding is that three of four reserve boundaries had Shallow gradients of decreasing abundance. This evidence, in general, suggests the existence of spillover in many cases (Abesamis et al. 2006).

The evidence for biological dispersal from marine reserves in Long Island, New York is another example. There was an experiment in which 90 blue cod were tagged and released at four sites, two of which were in and two of which were close to the closed areas (Cole et al. 2000). Cole et al. (2006) found fewer resightings of tagged fish occurred in the reserve than outside, but the resights in the reserve were larger on average than those outside. The saller number of resights in marine reserves suggests that the blue cod migrate longer distances in reserve sites than in fished areas. In other words, blue cod will grow larger sizes in marine reserves and help supply closed fisheries through spillover (Cole et al. 2000).

In addition, it is strongly predicted that marine reserves will allow spillover benefits in certain commercially species. For example, a study in New Zealand suggested that a small number of spiny lobsters in a given population will migrate large distances. Based on this evidence, it is likely that marine reserves can protect a significant percentage of the population of spiny lobsters while providing spillover benefits to surrounding fisheries (Davidson et al. 2002).

All in all, there are numerous existed examples of spillover in marine reserves.

(2) Provide a detailed history of the origins and objectives of no-take marine reserves.


The Great Barrier Reef (GBR) Marine Park covers an area of approximately 345,000 km², including a broken maze of over 2900 individual reefs, and 940 islands and coral cays. The reefs range enormously in size from <1 ha to more than 100 km², and those offshore range from flat, platform reefs to elongated ribbon reefs.

The GBR Marine Park comprises an amazing variety of communities and habitats, including mangrove estuaries, seagrass beds, algal and sponge “gardens”, sandy or muddy bottom communities, continental slopes and deep ocean troughs (Ref.). This extraordinary biological diversity and the interconnection of the habitats and species make the GBR and the surrounding areas one of the richest and most complex natural systems on earth. Although coral reef, mangrove and seagrass habitats occur elsewhere, no other marine protected area or World Heritage Area contains such biodiversity.

The Commonwealth (Federal) and State Governments have a cooperative and integrated approach to management of the GBRWHA built on an agreement signed in 1979. The Commonwealth Government is responsible for this area to manage this Marine Park (Ref.).

It is reported that the GBR supports a major part of Australia's economy with an estimated economic worth of more than A$1.2 billion per annum. Of which tourism provides about A$700 million per annum; commercial fishing around A$250 million per annum and the large recreational fishing and recreational boating sector is worth about A$270 million per annum (Ref.)

Since the Great Barrier Reef Marine Park Act was passed in 1975, the objective of the GBR Marine Park has been managed to (Ref.):

l Provide for the long-term protection and conservation of the environment and biodiversity of the GBR ecosystem, as included by the GBR World Heritage Area, and its transmission in good condition to future generations

l Allow ecologically sustainable use of the GBR ecosystem subject to the overarching objective of long-term protection and conservation

l Provide for meeting Australia's international responsibilities for the GBR World Heritage Area under the World Heritage Conservation.

In addition, in order to achieve these objectives, Queensland Government and Commonwealth try to (Ref.):

l Prohibit activities for the exploration and any drilling and mining within the Great Barrier Reef World Heritage Area.

l Maintain complementarity of relevant Commonwealth and Queensland management arrangements.

l Continue a Commonwealth/Queensland Ministerial Council to facilitate implementation and achievement of the objectives of this agreement.

l Continue joint action to halt and reverse the decline in quality of water entering the Great Barrier Reef.

(6) Review the literature on ecosystem recovery inside no-take marine reserves.

A: Several years of experience, areas where strict no-take regulations have shown some of the most positive ecological results of any management method. Such benefits can be seen in areas that have remained relatively pristine to long-term protection. Significant portions of the GBR off the Australian coast have been protected from human disturbance for over 30 years. Studies in no-take areas of the park show that the biomass of certain fish species has been maintained at levels up to several orders of magnitude higher than in nearby fished areas (Evans and Russ 2004).

Marine reserves have also been shown to facilitate the recovery of damaged ecosystems. For example, large areas of Georges Bank off the coast of Massachusetts were closed to fishing in 1995. The scientists began noting “steady and marked increase of fish in production” within a few years after the closure. In fact, the improved survival rate of the cod on Georges Bank was noted as the primary source of increased biomass for the four year period following the closure (Canadian Department of Fisheries and Oceans 1999). Generally, signs of recovery can appear quickly, sometimes within 2-5 years of the establishment of no-take area, and tend to persist for as long as protection remains in effect (Gell and Roberts 2003).

Furthermore, the benefits of no-take zones are ecosystem-based; that is, they are generally seen across a broad taxonomic range of organisms as well as in the improved state of the non-living habitat (Gell and Roberts 2003). These types of positive ecological results of no-take areas have been seen around the world, and are well documented in the scientific literature and well accepted by the majority of scientific communities.

In addition, marine reserves provide significant value for scientific research by comparing the outside changes with controlling areas. Long-established marine reserves provide researchers with a baseline healthy ecosystem that cannot be fully duplicated with any other methods. Even areas closed due to severe environmental damage can provide important data, such as the natural recovery rates of various species and habitats. Particularly, the data allows a quantitative judgment on the effectiveness of marine reserves in facilitating the recovery of fisheries and ecosystems (Hermens, Collie and Valentine 2003). This type of science that only marine reserves can provide is useful not only for examining and adjusting the MPAs themselves, but also for informing and improving management systems outside of reserves.

(7) Write a review of the social aspects of implementing no-take marine reserves.

A: Despite common assertions to the contrary, marine reserves can have significant economic benefits to society, including the assurance of long-term, sustainable fisheries. Admittedly, one of the unfortunate short-term effects of marine reserves is the displacement of fishermen due to the reduction of fishable waters, higher levels of congestion, and potential competition. However, in the long term, the establishment of a network of protected areas will inevitably create "optimal harvesting area[s]" with "higher resource rents" (Grafton, Komas, & Pham 2006) under controlled fishing rates.

From society's perspective, MPAs are a public investment of marine resources (Sanchirico 2000, Zinn and Buck 2001). The decision to commit resources can be guided by a benefit-cost framework that measures whether the potential benefits of protection outweigh the potential costs. Like other public investments, the potential benefits and costs of MPAs are realized both over the short and long run (Sanchirico et al. 2002).

Despite common assertions to the contrary, marine reserves can have significant economic benefits to society. Admittedly, one of the unfortunate short-term effects of marine reserves is the displacement of fishermen due to the reduction of fishable waters, higher levels of congestion, and potential competition. However, in the long term, the establishment of a network of protected areas will inevitably create "optimal harvesting areas" with "higher resource rents" (Grafton, Komas, & Pham 2006) under controlled fishing rates.

For example, closing off an area that historically contributed a significant catch would probably reduce the total catch. As population levels begin to recover in the MPA and spillover to the remaining fishable waters increases, total catch levels might increase (Sanchirico 1998).

Besides the protection of marine reserves, even more exciting are the beneficial economic effects of marine reserves through tourism and other non-exploitative activities. According to the National Marine Protected Areas Center (1995-1996), the Florida Keys National Marine Sanctuary and other marine-related parks and refuges provide an "estimated total tourist contribution to the economy of over 60 percent." Considering the scale of tourism in areas such as the Florida Keys, this is a truly significant percentage.

Another example of the economic benefits of marine reserves can be found in the Isles de Medes in Spain. The general beautification of the area and the simple presence of the reserve generated many tourism, research, and educational opportunities. A study undertaken by TERRA (2003) regarding the economic benefits to the area showed significant results. Over 30,000 beds were added to the hotel capacity of the area, while over 1200 new places of employment were created. Fiscally, additional revenue of 3 million Euros per year was earned by the local economy from tourism and recreational activities. Most importantly, an additional 2.5 million Euros of revenue was generated via visitors to the marine park itself.

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