Mismanaged Fisheries: Don’t forget the invertebrates

When we think of fisheries, we usually think of, well, fish.  As the collective global negligence regarding fisheries is further studied and exposed, these resource management issues have been brought out of obscurity in the past decade or so.  Fisheries worldwide totaled 15-20 million metric tons (MMT) in the 1950s, rising to ~85 MMT by the 1990s.  However, this was a non-linear ascent.  Global catch increased from 6% per year in the 1950s and 1960s and declined to 2% through the 1980s, finally falling to zero in the 1990s—all the while with increasing fishing effort.  We are reaching (or have already reached) the maximum productivity potential for the global ocean.  Estimates have placed world overcapacity at around 30%:  a measure of how much more money has been invested in fishing capacity than can be returned due to the oversupply of vessels.  Ironically, this cycle of overinvestment and overfishing is not economically viable.  Humans are essentially fishing out the watery realms of Earth, fundamentally restructuring enormous ecosystems, and it’s not even cumulatively profitable.  The value of all of the fish caught worldwide is ~70 billion USD but conservatively, the global catch costs 91-116 billion USD to attain.  Although pointed out in the early 1990s, no real global action has been taken and mechanisms such as government subsidies are necessary to keep things afloat.   The northern Atlantic, once home to long-lived, piscivorous (eats fish) fishes is now dominated by shorter-lived, plankivorous species, reflecting the industry’s predilection for high trophic-level fishes.  Interesting, considering that 90% of energy is lost at each successive trophic level1.  Globally, the ocean has lost 90% of all large pelagic fishes according to a 2003 study2–a staggeringly downward trend that even some marine scientists have struggled to accept but has since been further confirmed in other works3.

In the face of such utter enormity of human-caused pressures within global fisheries, much less attention has been focused on invertebrates, particularly invertebrates collected for purposes other than food.  For example, there is much contemporary interest in developing pharmaceuticals from marine invertebrates.  This is not a new idea.  These organisms have been collected and used for medicinal purposes at least since the 5th century BCE, being especially widespread in the ancient Greek and Byzantine periods.  Inverts were used for digestive, skin, and other issues, and were described by the likes of Hippocrates and Aristotle4.  In an aesthetic rather than utilitarian vein, precious corals have been used for decorative uses for thousands of years5.  Even throughout the second half of the 20th century, precious corals were harvested sporadically offshore of Oahu, Hawaii, among other global locales particularly on other Pacific islands and in the Mediterranean Sea.  The fishery in Hawaii includes some of the oldest animals on Earth; specimens of gold (Gerardia sp.) and black coral (Leiopathes sp.) have been radiometrically dated to be over 2700 years and 4200 years old, respectively 6.

A recent study delved into the oft-overlooked ornamental invertebrate fishery in Florida7.  Many aquarium hobbyists are no longer simply displaying fish-only tanks, opting instead to recreate microcosms of reef ecosystems.  The live coral (and ‘live rock’) trade alone is worth 200-330 million USD annually.  Little attention has been given to the impact that this coral and invertebrate collection has on Caribbean reefs, which sadly are among the worst off.  By Florida law, all commercial marine fisheries collections are to be reported; these data are compiled by the Florida Fish and Wildlife Conservation Commission.  Andrew Rhyne and colleagues used records from 1994-2007 to access the scale and general nature of this multi-species ornamental fishery.

Total landings were found to have increased drastically in this 13-year period, increasing by over half a million individuals each year.  Collectors do not target various invertebrate taxa uniformly:  in 2007, the top 15 species collected represented 92% of all landings; in 1994, the top 15 represented 88%.  The composition of these catches has shifted markedly due to the shift from purely ornamental specimens to species that can provide biological controls in reef tanks; however, fishing pressure on nearly every species has increased.  There’s also the question of removing individuals which perform an ecosystem function out of that environment.  6 million individuals were collected in 2007 that were considered grazers, which is more than double the landing reported for curio and ornamental purposes combined (figure below).  Grazers are popular because they control algal growth in tanks.  But they also provide this same ecosystem function in the ocean.  Less grazers means a less resilient reef and one that is increasingly likely to being overgrown by macroalgae.

Ecosystem processes and services in FLML invertebrates. Inlays show % of the total catch. From Rhyne et al. 2010.

Rhyne et al. propose that it may be most useful to manage this fishery by 1) species complexes, to avoid taxonomic ambiguities, and 2) considering single-species management strategies for the top 15 species collected and multi-species based strategies for the reminder.  Strangely, the gloomy economic climate seems to provide an apt time to implement new regulations.  The researchers note that

“Given the stark outlook for the global economy at the present time, and given that marine home aquaria are ‘‘luxury’’ expenditures, growth in ornamental fisheries is expected to slow or decrease. While industry demand is slow, a limited window of opportunity is open where management policies can change without immediate disruption of economic livelihood.”

Considering diversity and landings, Florida’s ornamental fishery is ranked third worldwide, only behind Indonesia and the Philippines. To date, this fishery operates with a licensing scheme under which most fishing is not affected by any current regulations.  For example, not granting any new licenses and reducing current licenses has only removed small-scale or inactive organizations.  The fact that only a few licenses are responsible for most of the fishery compounds this problem.  Can a collapse be avoided?  Hope seems to exist but the ultimate outcome is uncertain.  Fishermen within the Florida Keys Marine Sanctuary are calling for stricter regulations and the implementation of monitoring programs.  This work highlights the need to consider ornamental fisheries in the conservation and management of our marine resources.
This post was chosen as an Editor's Selection for ResearchBlogging.org

1. Helfman GS (2007) Fish Conservation: A Guide to Understanding and Restoring Global Aquatic Biodiversity and Fishery Resources. Island Press. Note that this is a secondary source (textbook) that discusses a multitude of papers in the primary literature. Most of the background on global fisheries discussed here was found within this work.
2. Myers RA, & Worm B (2003). Rapid worldwide depletion of predatory fish communities. Nature, 423 (6937), 280-3 PMID: 12748640
3. Jackson, J. (2008). Colloquium Paper: Ecological extinction and evolution in the brave new ocean Proceedings of the National Academy of Sciences, 105 (Supplement 1), 11458-11465 DOI: 10.1073/pnas.0802812105
4. Voultsiadou E (2010). Therapeutic properties and uses of marine invertebrates in the ancient Greek world and early Byzantium. Journal of ethnopharmacology, 130 (2), 237-47 PMID: 20435126
5. R Grigg (1993). Precious Coral Fisheries of Hawaii and the U.S. Pacific Islands Marine Fisheries Review, 55 (2), 50-60
6. Roark EB, Guilderson TP, Dunbar RB, Fallon SJ, & Mucciarone DA (2009). Extreme longevity in proteinaceous deep-sea corals. Proceedings of the National Academy of Sciences of the United States of America, 106 (13), 5204-8 PMID: 19307564
7. Rhyne, A., Rotjan, R., Bruckner, A., & Tlusty, M. (2009). Crawling to Collapse: Ecologically Unsound Ornamental Invertebrate Fisheries PLoS ONE, 4 (12) DOI: 10.1371/journal.pone.0008413


6 thoughts on “Mismanaged Fisheries: Don’t forget the invertebrates

  1. Its amazing that were bless of having so much marine life. To see them in wild will take your breath away. But human as we don’t know how to take care of them.We must not forget that their population are getting lesser and they need attention before its too late to save them.

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