Diggles busts Coral Sea myths

Elsewhere in News is a transcript of Fishing World’s recent interview with Pew’s Coral Sea Campaign director Imogen Zethoven – see story here. Marine biologist and Fishing World writer Dr Ben Diggles has been involved with the Queensland Game Fishing Association’s preparation of a position statement on the Coral Sea and offers his views below on issues raised in the interview.

(From interview)
Fishing World
: One of the big issues at the moment is climate change and how that it is having an impact on the global environment. How does the no fishing policy that you advocate protect reefs from climate change?

Pew’s Imogen Zethoven: There’s an increasing body of evidence from the science community that if you fully protect the ecosystem, then that ecosystem is more resilient to coral bleaching and increased sea surface temperatures. Perhaps one of the leading advocates of that in Australia is Professor Terry Hughes who has built up a very strong international reputation that shows coral reefs are able to recover if they haven’t been depleted of fish stocks. The concept of resilience is increasingly recognised and I’m sure you know this concept really well. It’s one of the primary arguments for putting aside areas for protection. In the end we recognise that if there’s runaway climate change then there’s nothing you can do. Given that we have some climate change locked in then there’s a necessity to increase the resilience of ecosystems – and that applies to terrestrial areas and marine areas – so they’re better able to withstand higher temperatures.

Dr Ben Diggles’ response:

This issue of fishing as it relates to “reef resilience” is one of several misleading positions that have been advocated by environmental groups such as Pew in recent times as they attempt to indiscriminately remove all forms of fishing from as much of the worlds oceans as they can. As usual, their method appears to be make lots of general overarching motherhood statements then back these up with selected scientific information based on poorly managed fisheries (including commercial and unregulated subsistence fishing and even use of dynamite and cyanide) to support their philosophy. They simply ignore science from well managed fisheries that does not support their narrow views, and refuse to discriminate between well managed recreational fishing (including catch and release fishing) and other less environmentally friendly fishing methods, such as trawling. I have reviewed some of the information being used by Pew and the Queensland Game Fishing Association has an excellent position statement that people should read on these and other issues in the Coral Sea. You can download this statement in our related news story here and visit the QGFA website at:
Let’s briefly look into a few of the myths in more detail below – you are urged to read the supporting documents and make up your own mind. (Please note numbering refers to reference details at bottom).

Myth: No fishing zones protect coral reefs from bleaching (1) or other coral diseases which are becoming more prevalent due to climate change.

Fact: No fishing zones do not protect reefs from coral disease or coral bleaching(2). A prime example of this in the Coral Sea region is at Lihou Reef, which is highly protected and has been closed to all fishing since 1982. Yet Lihou Reef has suffered severely from large scale coral bleaching in recent years with total coral cover reduced from 20 per cent to only 7.9 per cent between 1998 and 2002 (3,4). The available empirical evidence therefore shows no relationship between fishing and resistance to coral bleaching or other coral diseases in the Coral Sea (5). Coral bleaching occurs when corals are exposed to stressors such as abnormally high water temperatures, high UV levels, freshwater runoff, high nutrient levels, toxic chemicals from coastal runoff, sedimentation and disease (6). While many diseases of corals are recorded after stressful bleaching events, on the Great Barrier Reef there is evidence to show that bacterial infections are precursors to coral bleaching events initiated by periods of high water temperature (7). Clearly bleaching and diseases of coral are caused by environmental factors, hence establishment of no fishing zones will not protect coral reefs from damage from the environmental insults which are resulting from coastal development and climate change. The fact remains that without significant changes in land use practices and substantial progress from the rest of the world (including Australia) on abatement of greenhouse gases, the resulting rising sea levels, increasing water temperatures and ocean acidification will most likely result in serious damage to Coral Sea reefs in the next 50 years, irrespective of whether fishing occurs or not in all or part of the region.

Myth: No fishing zones protect herbivorous fishes (8) and therefore prevent dominance of coral reefs by microalgae and increase “reef resilience” (which is the ability of coral reefs to recover from coral mortality events).

Fact: While no fishing zones provide protection for herbivorous reef fishes from fishing, this does not necessarily translate into increased “reef resilience”, particularly as predatory fish eat herbivorous fishes and some herbivorous species (e.g. parrotfish) eat corals as well as algae. Indeed; mortality of coral is usually a prerequisite for algal overgrowth of coral to occur – loss of herbivorous fishes does not directly kill coral (9). Some research has shown that in locations in the Carribbean and Pacific Islands where herbivorous fishes are intensively targeted by subsistence or commercial fishing, increased densities of herbivorous fish in a no take MPA controlled macroalgal growth after widespread coral mortality from bleaching (10). However, other studies have found no difference in macroalgal abundance between no-take reserves and reference sites open to fishing (11). Indeed no take MPAs may not halt coral declines, nor enhance coral recovery(12,13). Large scale bleaching events and tropical storms which cause widespread coral mortality are usually followed by widespread overgrowth of macroalgae. This probably occurs because herbivore populations, even on unfished reefs, require relatively long time periods to increase in abundance in response to large changes in their food supply. This is why several prominent coral reef scientists have stated “Judging from recent observations of the extent of coral mortality from disease and bleaching, there is every reason to suspect that under such circumstances higher levels of herbivory will have little or no influence on coral recovery”(14).

Myth: Fishing for pelagic fishes degrades the ability of coral reefs to recover from coral mortality events.

Fact: Game fishers and sport fishers in the coral sea target pelagic fish species using rod and line and release most of their catch. There is no evidence in the scientific literature that demonstrates direct linkages between well managed recreational line fishing (as opposed to subsistence or commercial fishing where most/all fish are killed for food) for pelagic fishes and the ability (or otherwise) of coral reefs to recover from outbreaks of coral bleaching or coral diseases. Indeed, in some “no take” marine protected areas under USA jurisdiction, catch and release recreational fishing is still permitted (e.g. bonefish in Palmyra Atoll (15)) as it can generate valuable economic activity with negligible environmental footprint while also generating valuable research outcomes. Certainly in some parts of the world there are issues such as overfishing of herbivorous fishes (which otherwise can help control algal overgrowth) by subsistence fishers. However, with no permanent human habitation in the Coral Sea, the overfishing of herbivorous fishes does not occur and this issue is therefore irrelevant. Certainly, overfishing of spawning aggregations of demersal reef fishes is an issue which requires attention in many parts of the world. However, the latter problem responds to conventional fisheries management techniques such as closed seasons and/or small closed areas located specifically to protect spawning aggregation sites. Research is required to actively pinpoint the location and timing of any such aggregations. Furthermore, none of these issues are relevant to the activities of game fishers and sport fishers in the Coral Sea who target carnivorous game fishes such as billfish, tunas, giant trevally and other pelagics, releasing most of their catch. Research shows that survival of these released fish, especially those taken on artificial lures in shallow water, is very high (usually over 90 per cent and often approaching 100 per cent if best practice release methods are used (16)), such that this form of recreational fishing is completely sustainable and has minimal effect on coral reef ecosystems.

Myth: The Coral Sea is not “protected” from fishing.

Fact: There are already 17300 km2 of no fishing areas in the Coral Sea region, encompassing a variety of reef formations including the largest reef structures in the region (Lihou and Coringa-Herald National Nature Reserves). This represents over 60% of the available reef platform and coral bank area in the Coral Sea region that is already closed to fishing, which exceeds even the maximum 50% level of protection suggested by advocates of MPAs designed using comprehensive, adequate and representative (CAR) principles. Any “need” for additional no fishing areas in the region cannot be justified until such time that it is conclusively shown that the existing reserves are not adequate or effectively achieving their management goals. Good quality, well funded research by independent scientists is critical to this process of evaluating the effectiveness of existing no fishing areas in the region.
Furthermore, the fish assemblages in the areas of the Coral Sea that remain open to fishing are already well protected from recreational fishing by a suite of bag and size limit regulations managed by the Queensland Department of Primary Industries (QDPI) (17) . For example since 2003 the take and possession of Maori wrasse, potato cod, barramundi cod, Queensland groper, red bass, Chinaman fish and paddletail has been prohibited. All coral reef fin fish species have a minimum size limit of 25cm unless otherwise specified, and all coral reef fin fish species have possession limits of 5 unless otherwise specified. Sharks and rays have a maximum size limit 1.5 m and a number of vulnerable shark species are protected in Queensland waters. It is clear that recreational fishing in Queensland waters is highly regulated and well managed in comparison to recreational and subsistence fishing in the other areas of the world where Pew and other environmental groups are drawing the majority of their research information from.

Myth: Permanent no fishing zones are the best and only way to enhance populations of reef fish.

Fact: Permanent fishing closures are not the only or even “best” way to enhance populations of reef fish. Indeed, scientists have shown that areas under some forms of traditional management where fishing is permitted either some or all of the time were the ones with the largest sized and numbers of reef fish (18). The authors of that study concluded “Contrary to the widely accepted idea that permanent closures are the most effective ways to improve reef ecosystem health, none of the traditional management regimes involved permanent reef closures. Each involved periodic closures, whereby protected reefs were periodically opened to fishing, either briefly or for extended periods of time, and one of these systems actually allowed line fishing inside the protected area throughout the entire year”. Other studies have clearly demonstrated how MPAs failed to protect reef fish biodiversity in areas where widespread coral mortality has occurred (19). Permanent fishing closures which implement the “lock it away and forget it” approach not only fail to protect coral reefs from the main threats to coral health (pollution and climate change), but also present a poor management option when it comes to optimising protection of fish stocks when compared to adaptive management arrangements which allow some fishing on a sustainable basis. This has been realised in the USA where a recent Presidential Executive Order has required federal conservation agencies to maintain recreational fishing access on federal lands and waters, including within marine protected areas (20).

Myth: That the Coral Sea holds little significance to the average recreational fisher.

Fact: The Coral Sea is remote and difficult to access by the average recreational fisher. Only individuals who have access to large private boats or can afford a long distance charter can access the reefs in this region. However this does not mean that the Coral Sea holds little significance to the average recreational fisher. Indeed, the reverse is the case. Such is the quality of the fishing for pelagic sportfish in the region, the Coral Sea is a magnet for recreational fishers from not only Australia, but around the globe. For many people a trip to the area represents a once in a lifetime fishing opportunity, an irreplaceable experience which equates in many ways to how mountain climbers view an expedition to Mount Everest. Certainly, the socio-cultural value of the Coral Sea can only be maximised by continuing to allow recreational fishing access. Just as mountain climbers are managed to allow them to experience places like Everest, appropriately managed recreational fishing is an entirely sustainable and legitimate activity which will not threaten the ecosystem or degrade the natural qualities which draw people to the Coral Sea region.

References: (1) Coral bleaching is loss of the symbiotic algae andphotosynthetic pigments which give corals their energy and colour.
(2)Aronson RB, Precht WF (2006). Conservation, precaution, and Caribbeanreefs. Coral Reefs 25: 441-450.
(3) Pew Charitable Trust (2008). An Australian Coral Sea Heritage Park. Zethoven I (ed). p20.
(4) Oxley WG and 3 co-authors (2004). Marine Surveys undertaken in the Lihou Reef National Nature Reserve, March 2004. AIMS
(5) While destructive fishing with cyanide or explosives is well known to cause both fish and coral mortality, these forms of fishing are not relevant to the Coral Sea region nor are they condoned in any way by the QGFA, hence they will not be considered further in this document.
(6) Grimsditch and Salm (2006). Coral reef resilience and resistance to bleaching. ICUN science group working paper ser. 1.
(7) Bourne D et al. (2008). Changes in coral associated microbial communities during a bleaching event. The ISME Journal 2: 350-363.
(8) Herbivorous reef fishes feed mainly on algae and corals. Some of these include members of the families Scaridae (parrotfish), Siganidae (rabbitfish) , Chaetodontidae (butterflyfishes) and Acanthuridae (surgeonfishes).
(9) Aronson RB, Precht WF (2006). Conservation, precaution, and Caribbean reefs. Coral Reefs 25: 441-450.
(10) Mumby PJ and 13 co-authors (2006). Fishing, trophic cascades, and the process of grazing on coral reefs. Science 311:98-101
(11) Miller MW, Aronson RB, Murdoch TJT (2003) Monitoring coral reef macroalgae: different pictures from different methods. Bulletin of Marine Science 72: 199-206
(12) McClanahan TR and 8 co-authors (2001). Responses of algae, corals and fish to the reduction of macroalgae in fished and unfished patch reefs of Glovers Reef Atoll, Belize. Coral Reefs 19: 367-379.
(13) McClanahan TR, and 4 co-authors (2005). Detriments to post-bleaching recovery of corals. Coral Reefs 24: 230-246.
(14) Aronson RB, Precht WF (2006). Conservation, precaution, and Caribbean reefs. Coral Reefs 25: 441-450.
(15) A.M. Friedlander, et al.(2008). Biology and Ecology of the Recreational Bonefish Fishery at Palmyra Atoll National Wildlife Refuge with Comparisons to Other Pacific Islands. In: Ault JS (2008). Biology and Management of the World Tarpon and Bonefish Fisheries. 441 pgs.
(16) Diggles, B. K. and Ernst, I. (1997). Hooking mortality of two species of shallow water reef fish caught by recreational angling methods. Marine and Freshwater Research 48: 479-483. , and Danylchuk et al. (2007). Post-release mortality of bonefish, Albula vulpes, exposed to different handling practices during catch-and-release angling in Eleuthera, The Bahamas. Fisheries Management and Ecology 14: 149-154.
(18) McClanahan et al. (2006). A comparison of Marine Protected Areas and alternative approaches to coral reef management. Current Biology 16: 1408-1413.
(19) Jones GP, and 3 co-authors (2004). Coral decline threatens fish biodiversity in marine reserves. Proc. Natl. Acad. Sci. USA 101: 8251-8253.



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