Groping with Multiple Risks on Grouper Populations, by Don Orth

According to the FAO, fisheries provide at least 15% of the animal protein consumed directly or indirectly by humans.  As demand grows we must deal with the fact that fishing drives down fish populations leading to a global fisheries crisis. John Shepherd, a fisheries biologist, once said “Managing fisheries is hard: it’s like managing a forest, in which the trees are invisible and keep moving around.”   Fisheries on groupers are even harder to manage.

Overfishing is driven by biological and social factors.  Therefore, fisheries management must be grounded in principles of fisheries science melded with social-ecological theories.  In this post, I explore this fundamental truth as it plays out in the management of grouper fisheries throughout the world.    Groupers are fish in the subfamily Epinephelinae (Serranidae) that are widely distributed in warm seas.   Familiar genera include the Epinephelus and Mycteroperca.

 

Black Grouper Mycteroperca bonaci  Photo by Alfonso Gonzalez   Flickr

Changing density and size structure of reef fish top predators, such as groupers, is often observed but in subtropical and tropical nations there may be no official landings records.   But local fishers are often aware of declines, reporting that grouper catches were abundant many years ago (Aguilar-Perera et al. 2009; Amorim et al 2018; Bender et al. 2014).  So managers must struggle to manage without a fair determination of baseline conditions (Pinnegar and Engelhard 2008). 

Food and Agricultural Organization of the United Nations (FAO) capture production landings data for groupers 1950–2009. (Sadovy de Mitcheson et al. 2013) 

Vulnerability and value lead to rapid depletion and overfishing in snapper and grouper (Coleman et al 2000; Sadovy de Mitcheson et al. 2013).  Groupers are highly regarded for the mild quality of their flesh. Therefore, they are most heavily exploited among other high-priced reef fishes.  Vulnerability is related to ease of capture and a slow life history.  Most species take a long time to attain high reproductive values. In shallow coral reefs many groupers can easily be approached and speared by spear fishers, hook and line, and cyanide. Fisheries target adults captured and marketed directly for food, but also juveniles for mariculture grow-out operations (Sadovy and Pet 1998). Because it takes a long time to obtain needed life history information, fisheries independent survey data, and catch history, the groupers may be overfished long before data are even available for a stock assessment. 

 

Trends in largest fish caught (a) and highest daily catch (b) for Black Grouper  (Bender et al. 2014). 

Value to humans is related to wide cultural acceptance of the grouper and other human demographics, such as distance to markets and local human population density.  Of the 163 species of groupers, 20 risk extinction if current trends continue, and an additional 22 species are considered to be Near Threatened (Sadovy de Mitcheson et al. 2013). Because of its popularity, groupers are often mislabeled or substituted with lower valued fish.  Over 50 species of groupers worldwide may be marketed and sold in the US as grouper (FDA Seafood List).  Here are tips for avoiding fake grouper.

Pan fried grouper. Photo by Kirk K. Flickr

If slow life history and high value create a double jeopardy for groupers, one additional trait adds a triple jeopardy condition.   Groupers display predictable spawning aggregations, temporary gatherings of large numbers of grouper for spawning.   These spawning aggregations make groupers extremely vulnerable at the same time when reproductive values are highest (Erisman et al. 2017).   Watch this video of a spawning rush of groupers.   Groupers move around and local fishers learn their patterns and can use GPS to re-locate these locations and target the spawning aggregations. Fisher knowledge will influence the extent to which aggregations are perceived as predictable and exploited by fishers (Robinson et al 2014). In some cases, fishers have known for centuries where and when aggregations form (Erisman et al. 2017).  Therefore, effective management requires understanding and consideration of life history, and ecological and socioeconomic drivers.     

Echogram depicting the locations of spawning aggregation of Nassau Grouper (red) and Horse-eye Jacks (blue) along transect off Little Cayman Island   (Egerton et al. 2017)

The collapse of the now endangered Nassau Grouper Epinephelus striatus was due to overfishing on spawning aggregations.   The population collapse resulted in the loss of an important fishery and many spawning aggregations.  Grouper supported many Bahamians for centuries, currently providing over $1 million in landings per year,  and are part of the social fabric (Stump et al. 2017).

Spawning aggregations have indirect effects on marine ecosystems.  Eggboons are large though temporary concentrations that provide highly nutritious fatty acids that suppport multiple trophic levels. Loss of groupers translates to a loss of trophic redistribution via eggboons (Fuiman et al. 2015).

Eggboons from grouper spawning aggregations create immense redistribution of trophic resources to all lower trophic levels.  Dashed arrows represent typical trophic pathways and solid arrows represent flow through eggboons (Fuiman et al. 2015).

From numerous investigations on grouper fisheries throughout the world, we are more aware of the challenges.   In particular, we need to examine how to add the social and cultural aspects to fisheries management efforts.  Examining local fishers knowledge of local groupers may provide better understanding of historical baselines (Robinson et al. 2014).

(Top) A catch of Atlantic Goliath Grouper made on the charter boat Gulfstream in the 1950's. Photo from the Wil-Art Studio, gift of Angie Marine. Florida Keys Public library.   (Bottom) Spearfishing catches in a single day in 1972 at fishing village in southeastern Brazil (Giglio et al. 2017).

The functional extinction of the critically endangered Atlantic Goliath Grouper in many parts of the  range has attracted much attention and fishing moratoria are in place. Recovery of populations depend on conditions in nursery areas (Koenig et al. 2007; Shideler et al. 2015; Lobato et al. 2016) and at far distant spawning aggregations. Research that combines local ecological knowledge and takes advantage of technologists, such as bioacoustics, biotelemetry, sonar, and remote and autonomous underwater vehicles may lead to more accurate information on grouper spawning aggregations (Erisman et al. 2017).   Photo-identification is widely used for non-invasive mark-recapture analysis and appears to be well suited for the sedentary, large Goliath Grouper in marine parks frequented by divers (Hostim-Silva et al. 2017).

Photos and corresponding sketches of Goliath Grouper heads used for individual recognition (Hostim-Silva et al 2017)  

In closing, fishing and lack of effective management leads to rapid overfishing of many species of groupers.  Many measures are being implemented, such as minimum and slot size limits, recreational bag limits, commercial fishing quotas, gear and seasonal controls, marine protected areas, and limited entry, the effectiveness will depend on local context.  Illegal fishing continues to be a problem (Giglio et al. 2014).  In the case of the critically endangered Atlantic Goliath Grouper, we need to:  (1) protect coastal lagoons with fringing mangrove nursery areas; (2) locate spawning aggregations and learn from traditional ecological knowledge; (3) adopt large no-take protected areas and evaluate diving tourism as the presence of large, emblematic fish is an attraction (Heyman et al. 2010; Shideler and Pierce 2016); and (4) halt poaching.  However, leadership, social networks, and co-management at the local level are the glue that will make these plans successful (Gutiérrez et al. 2011).  There are signs of recovery off  Florida where a fishing moratorium on Atlantic Goliath Grouper has been in place since 1990.  Grouper are only one of many valuable residents of threatened coral reef ecosystems. Restoring coral reefs will require reducing and reversing carbon emissions that are driving global climate change (Knowlton and Jackson 2008). 

  . 

References

Amorim, P., P. Sousa, M. Westmeye, G.M. Menezes. 2018. Generic knowledge indicator (GKI): A tool to evaluate the state of knowledge of fisheries applied to snapper and grouper.   Marine Policy 89:40-49.

Aguilar-Perera, A., C. González-Salas, A. Tuz-Sulub, and H. Villegas-Hernández. 209.  Fishery of the Goliath grouper, Epinephelus itajara (Teleostei: Epinephelidae) based on local ecological knowledge and fishery records in Yucatan, Mexico. International Journal of Tropical Biology  57:557–566.

Bender, M.G., G.R. Machado, P.J.A. Silva, S.R. Floeter, C. Monteiro-Netto, O.J. Luiz, and C.E.L. Ferreira.  2014. Local ecological knowledge and scientific data reveal overexploitation by multigear artisanal fisheries in the southwestern Atlantic. PLoS ONE 9(10): e110332. doi:10.1371/journal.pone.0110332

Coleman, F.C., C.C. Koenig, G.R. Huntsman, J.A. Musick, A.M. Eklund, J.C. McGovern, G.R. Sedberry, R.W. Chapman, and C.B. Grimes. 2000. Long-lived reef fishes: the grouper-snapper complex. Fisheries 25:14–21.

Egerton, J.P., A.F. Johnson, L. LeVay, C.M. McCoy, B.X Semmens, S.A. Heppell, and J.R. Turner. 2017. Coral Reefs 36:589-600.

Erisman, B., W. Heyman, S. Kobara, T. Ezer, S. Pittman, O. Aburto-Oropeza, and R.S. Nemeth. 2017. Fish spawning aggregations: where well-placed management actions can yield big benefits for fisheries and conservation. Fish and Fisheries 18 128–144.

FAO. 2009. The state of world fisheries and aquaculture 2008. FAO Fisheries Department. Rome (Italy) 162 p.

Fuiman, L.A., T.L. Connelly, S.K. Lowerre-Barbieri, and J.W. McClelland. 2015. Egg boons: central components of marine fatty acid food webs. Ecology 96:362–372.

Giglio, V.J., A.A. Bertoncini, B.P. Ferreira, M. Hostim-Silva, and M.O. Freitas. 2014.  Landings of goliath grouper, Epinephelus itajara, in Brazil: despite prohibited over ten years, fishing continues.  Brazilian Journal of Nature Conservation 12:118-123.

Giglio, V.J., M.G. Bender, C. Zapelini, and C.E.L. Ferreira. 2017.  The end of the line? Rapid depletion of a large-sized grouper through spearfishing in a subtropical marginal reef. Perspectives in Ecology and Conservation 15:115-118.  
Gutiérrez, N.L. R. Hilborn, and O Defeo. 2011. Leadership, social capital and incentives promote successful fisheries. Nature DOI: 10.1038/nature09689

Heyman,W.D., Carr, L.M., Lobel, P.S., 2010. Diver ecotourism and disturbance to reef fish spawning aggregations: it is better to be disturbed than to be dead. Marine Ecology Progress Series 419, 201e210. http://dx.doi.org/10.3354/meps08831.
Hostim-Silva, M., A.A. Bertoncini, M. Borgonha, J.R. Leite, M.O. Freitas, F. A. Daros, L. S. Bueno, A. P. C. Farro, and C. C. Koenig. 2017.  The Atlantic Goliath Grouper: Conservation strategies for a critically endangered species in Brazil.   Pages 367-405 in M.R. Rossi-Santos, and C. W. Finkl, editors, Advances in Marine Verebrate Research in Latin America.  Springer.

Knowlton, N, and J.B. Jackson. 2008. Shifting baselines, local impacts, and global change on coral reefs. PLoS Biology 6: e54.
Koenig, C.C., F.C. Coleman, A.-M. Eklund, J. Schull, and J. Ueland, 2007.  Mangroves as essential nursery habitat for the goliath grouper (Epinephelus itajara).   Bulletin of Marine Science 80:567-585.

Lobato, C.M.C., B.E. Soares, T.O.R. Begot, and L.F. de Assis Montag. 2016. Tidal pools as habitat for juveniles of the goliath grouper Epinephelus itajara (Lichtenstein 1822) in the Amazonian coastal zone, Brazil.  Brazilian Journal of Nature Conservation 14:20-23. 
Sadovy, Y., and J. Pet.1998.  Wild collection of juveniles for grouper mariculture: just another capture fishery?  Live Reef Fish Information Bulletin 4:36-39

Sadovy de Mitcheson, Y., M.T. Craig, A.A. Bertoncini, K.E. Carpenter,W.W.L. Cheung, J.H. Choat, A.S. Cornish, S.T. Fennessy, B.P. Ferreira, P.C. Heemstra, M. Liu, R.F. Myers, D.A. Pollard, K.L. Rhodes, L.A. Rocha, B.C. Russell, M.A. Samoilys, and J. Sanciangco. 2013. Fishing groupers towards extinction: a global assessment of threats and extinction risks in a billion dollar fishery. Fish and Fisheries 14:119–136. http://dx.doi.org/10.1111/j.1467-2979.2011.00455.x.

Mora, C., R.A. Myers, M. Coll, S. Libralato, T.J. Pitcher, R.U. Sumaila, D. Zeller, R.Watson, K.J. Gaston, B. Worm. 2009. Management effectiveness of the world's marine fisheries, PLoS Biology 7 e1000131, http://dx.doi.org/10.1371/journal.pbio.1000131.

Pinnegar, J.K., G.H. Engelhard. 2008. The ‘shifting baseline’ phenomenon: a global perspective. Reviews in Fish Biology and Fisheries 18: 1–16.

Robinson, J., J.E. Cinner, and N.A.J. Graham. 2014.  The influence of fisher knowledge on the susceptibility of reef fish aggregations to fishing.   PLOS ONE  9(3): e91296.

Robinson, J., N.J. Graham, J.E. Cinner, G.R. Almany, P. Waldie. 2015. Fish and fisher behaviour influence the vulnerability of groupers (Epinephelidae) to fishing at a multispecies spawning aggregation site. Coral Reefs 34:371–382.

Shideler, G.S., S.R. Sagarese, W.J. Harford, J.Schull, and J.E. Serafy. 2015. Assessing the suitability of mangrove habitats for juvenile Atlantic goliath grouper. Environmental Biology of Fishes  98:2067-2082.
Shideler, G.S., and B. Pierce. 2016.  Recreational diver willingness to pay for goliath grouper encounters during the months of their spawning aggregation off eastern Florida, USA.  Ocean and Coastal Management 129:36-43.

Stump, K., C.P. Dahlgren, K.D. Sherman, C.R. Knapp. 2017. Nassau grouper migration patterns during full moon suggest collapsed historic fish spawning aggregation and evidence of an undocumented aggregation.  Bulletin of Marine Science 93:375-389.