Tunas and their fisheries: safeguarding sustainability in the twenty-first century
- 1.9k Downloads
The relationship of tunas to their environment (i.e. the effects of oceanographic conditions on movements, distribution, and catchability) has been a topic of interest for decades (e.g. Barkley et al. 1978; Sund et al. 1981). This area of investigation is now becoming increasingly important as the effects of climate change becomes more apparent in the pelagic environment (e.g. Kimura et al. 2010; Lehodey et al. 2011; Hobday et al. 2013). Recent studies relating climate change to changes in movements and distributions of tunas (e.g. Del Raye and Weng 2015; Mislan et al. 2017) are built on the foundation of physiological studies on tunas undertaken specifically to define the characteristics of species-specific suitable habitats, as well as environmental conditions that restrict movements and distribution (reviewed by Brill 1994 and Bernal et al. 2017).
Interweaving of the disparate scientific disciplines of tuna physiology and fishery science (e.g. Brill et al. 2005; Brill and Lutcavage 2001) has also led to significant efforts to correct catch-per-unit effort data by differentiating changes in apparent abundance (i.e. population size) from changes in catchability (e.g. Bertrand et al. 2002; Bigelow et al. 2002; Bigelow and Maunder 2007). The importance of modelers, fishery biologists, and physiologists working interactively is now recognized as being necessary to translate mechanistic physiological understanding into effective fisheries management and conservation strategies (Hobday et al. 2013; Horodysky et al. 2015, 2016; McKenzie et al. 2016). These types of inter-disciplinary collaborations include predictions of the effects of oceanographic conditions on the distributions of different tuna species and thus their vulnerability to specific fishing gear (e.g. Hobday 2010; Lehodey et al. 2015). Despite decades of study, there is still much to understand. New technologies are, however, playing an important role in elucidating trophic dynamics and species-specific reliance on different trophic pathways (Young et al. 2015; Duffy et al. 2017).
Several of the reviews in this issue also provide syntheses of the species-specific spawning habitats, feeding ecologies, vertical movements, and migratory patterns of targeted tuna species with the objectives of elucidating both commonalities and differences. Given the economic importance of the fisheries exploiting tunas, and the continuing changes in the environmental conditions of the pelagic environment in the twenty-first century, most papers also take into account the likely impacts of changes in climate and fishing pressure—critical for ensuring sustainability. More specifically, Muhling et al. (2017) summarize the reproductive movements and habitats sought by breeding tunas, many of which have restricted spawning grounds (e.g. Richardson et al. 2016). The impact of climate change on spawning regions may lead to declining spawning activity and movement to new areas (e.g. Muhling et al. 2015, 2016), which will be a challenge for management and assessment.
As with movements between feeding and spawning grounds, the growth rates of tunas varies between the tropical and temperate species group (e.g. Fromentin and Fonteneau 2001). Murua et al. (2017) describe the age-specific patterns of growth, and implications for population dynamics and fisheries management. They show that tunas have evolved different growth strategies which have implications for fisheries management. Species with faster growth rates generally support higher catch levels than species with slower growth rates, which can be problematic when multiple species are targeted in the same fishery. Specific syntheses of information on yellowfin tuna is presented by Pecoraro et al. (2017), while Nikolic et al. (2017) cover albacore tuna. Both contributions describe the biology, ecology, fisheries status, stock structure and management of these species. While much is known, environmentally-driven changes in stock distribution still needs to be integrated into their respective stock assessments. This integrated understanding of biology, fisheries and the economic forces driving exploitation is required for effective international management and conservation.
The changing nature of tuna fisheries are not just about tuna biology nor national and international regulation. The interactions of tuna fisheries with bycatch species, is also driving the restriction of areas and times of operation, and specific gear configurations. Hall et al. (2017) describe bycatch trends and patterns in tuna fisheries, along with approaches being implemented to reduce bycatch. Importantly, they describe market strategies and stakeholder education efforts that are often overlooked in bycatch management.
The local, regional and global markets obviously influence tuna fisheries, with economic forces and supply chains relatively underappreciated in research to date (Mullon et al. 2017). Tuna products are amongst the most widely traded seafood with global trade established early in the development of tuna fisheries (Fig. 1). Guillotreau et al. (2017) report a high degree of market integration and competition through prices at the global level and address a range of questions related to consumer responses to price changes, economic incentives for quota reduction and targeting of tuna species according to the relative price.
Collectively, the reviews presented herein build on recent compilations of tuna research (Kitagawa and Kimura 2015; Hobday et al. 2017), which was reinvigorated in the early 2000 s with large scale tagging programs (e.g. Block et al. 2003) and the initiation of the Climate Impacts on Oceanic Top Predators (CLIOTOP) research program (Lehodey and Maury 2010). To sustain tuna harvests and sustainable populations into the twenty-first century, however, greater attention must be given to continuing integration of disparate areas of study and biological organization—from physiology to movements, harvests to fisheries management and effective resource and conservation strategies, and eventually to markets and consumers.
We are grateful to all the authors and the referees who provided reviews of these special issue papers, and the assistance of the editor-in-chief.
- Barkley RA, Neill WH, Gooding RM (1978) Skipjack tuna, Katsuwonus pelamis, habitat based on temperature and oxygen requirements. Fish Bull 76:653–662Google Scholar
- Bernal D, Sepulveda C, Musyl M, Brill R (2009) The eco-physiology of swimming and movement patterns of tunas, billfishes, and large pelagic sharks. In: Domenici P, Kapoor BG (eds) Fish locomotion: an etho-ecological approach. Science Publishers, Enfield, pp 436–483Google Scholar
- Bernal D, Brill RW, Dickson KA, Shiels HA (2017) Sharing the water column: physiological mechanisms underlying species-specific habitat use. Rev Fish Biol Fish (this issue)Google Scholar
- Block BA, Stevens ED (2001) Fish physiology, Vol. 19, tuna—physiology, ecology and evolution. Academic Press, San DiegoGoogle Scholar
- Block BA, Costa DP, Boehlert GW, Kochevar RE (2003) Revealing pelagic habitat use: the tagging of Pacific pelagics program. Oceanol Acta 5:255–266Google Scholar
- Brill R, Lutcavage M (2001) Understanding environmental influences on movements and depth distribution of tunas and billfish can significantly improve stock assessments. In: Sedberry GR (ed) Island in the stream: oceanography and fisheries of the Charleston Bump. Am Fish Soc Symposium Bethesda, MD 25, pp 179–198Google Scholar
- Brill RW, Bigelow KA, Musyl MK et al (2005) Bigeye tuna behavior and physiology… their relevance to stock assessments and fishery biology. Col Vol Sci Pap ICCAT 57:142–161Google Scholar
- Gaertner D, Delgado de Molina A, Ariz J, Pianet R, Hallie J (2008) Variability of the growth parameters of the skipjack tuna (Katsuwonus pelamis) among areas in the eastern Atlantic: analysis from tagging data within a meta-analysis approach. Aquat Living Resour 21(1649):349–356CrossRefGoogle Scholar
- Gaikov VV, Chur VN, Zharov VL, Fedoseev PY (1980) On age and growth of the Atlantic bigeye tuna. Col Vol Sci Pap ICCAT 9:294–302Google Scholar
- Guillotreau P, Squires D, Sun J, Compeán GA (2017) Local, regional and global markets: what drives the tuna fisheries? Rev Fish Biol Fish (this issue)Google Scholar
- Hall M, Gilman E, Minami H et al (2017) Mitigating bycatches in tuna fisheries. Rev Fish Biol Fish (this issue)Google Scholar
- Lehodey P, Maury O (2010) Climate impacts on oceanic top predators (CLIOTOP): introduction to the special issue of the CLIOTOP international symposium, La Paz, Mexico, 3–7 December 2007. Prog Ocean 86:1–7Google Scholar
- Lehodey P, Hampton J, Brill RW et al (2011) Vulnerability of oceanic fisheries in the tropical Pacific to climate change. In: Bell J, Johnson JE, Hobday AJ (eds) Vulnerability of tropical pacific fisheries and aquaculture to climate change. Secretariat of the Pacific Community, Noumea, pp 433–492Google Scholar
- Mislan KAS, Deutsch CA, Brill RW, Dunne JB, Sarmiento JL (2017) Predicted consequences of climate change on vertical habitat availability of tunas based on species-specific differences in blood oxygen affinity. Glob Change Biol (in press)Google Scholar
- Muhling BA, Lamkin JT, Alemany F et al (2017) Reproduction and larval biology in tunas, and the importance of restricted area spawning grounds. Rev Fish Biol Fish (this issue)Google Scholar
- Murua H, Rodríguez-Marin E, Neilson J et al (2017) Fast versus slow growing tuna species—age, growth, and implications for population dynamics and fisheries management. Rev Fish Biol Fish (this issue)Google Scholar
- Nikolic N, Morandeau G, Hoarau L et al (2017) Review of albacore tuna, Thunnus alalunga, biology, fisheries and management. Rev Fish Biol Fish (this issue)Google Scholar
- Pecoraro C, Zudaire I, Bodin N et al (2017) Putting all the pieces together: integrating current knowledge of the biology, ecology, fisheries status, stock structure and management of yellowfin tuna (Thunnus albacares). Rev Fish Biol Fish (this issue)Google Scholar
- Schaefer KM, Fuller DW (2002) Movements, behavior, and habitat selection of bigeye tuna (Thunnus obesus) in the eastern equatorial Pacific, ascertained through archival tags. Fish Bull 100:765–788Google Scholar
- Schaefer KM, Fuller DW, Block BA (2009) Vertical movements and habitat utilization of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye (Thunnus obesus) tunas in the equatorial eastern Pacific ocean, ascertained through archival tag data. In: Nielsen JL, Arrizabalaga H, Fragoso N, Hobday A, Lutcavage M, Sibert J (eds) Tagging and tracking of marine animals with electronic devices. Springer, Netherlands, pp 121–144CrossRefGoogle Scholar
- Sund PN, Blackburn M, Williams F (1981) Tunas and their environment in the Pacific Ocean: a review. Oceanogr Mar Biol Ann Rev 19:443–512Google Scholar
- Wild A (1986) Growth of yellowfin tuna, Thunnus albacares, in the eastern Pacific Ocean based on otolith increments. Inter Am Trop Tuna Comm Bull 18:421–482Google Scholar