Age, Growth, Diet, and Reproductive Biology of the Tripletail, Lobotes surinamensis, From the North-Central Gulf of Mexico

Tripletail, Lobotes surinamensis, are migratory fish that occur worldwide in warm seas, including the Gulf of Mexico and Caribbean. In the north-central Gulf of Mexico, tripletail support small recreational and commercial fisheries from April to Oct. and are commonly caught in bays and estuaries. Few studies have evaluated the life history and biological characteristics of tripletail; therefore, the objective of this study was to examine the age and growth, reproductive biology, and diet of tripletail caught off coastal Alabama. Our primary goal was to use life history information to determine. a minimum size limit for harvest. A secondary goal was to compare the results of our study with those of previous tripletail studies. A total of 119 specimens, ranging in size from 293- to 763-mm total length (TL), were collected from recreational anglers and from a wholesale seafood dealer between May 1998 and Aug. 2000. Female specimens were significantly longer and heavier than males. Total length varied greatly with age, although significant overlap in lengths was observed among ages. Age ranged from 0.87 to 4.09 yr. No male was older than 3.15 yr of age, whereas five females were estimated to be more than 4 yr old. Fifty percent of females reached sexual maturity by 494- to 594-mm TL and approximately 1 to 2 yr of age. All males greater than 380 mm were sexually mature. Diets were composed primarily of penaeid shrimps, various pelagic fish species, and portunid crabs, with the proportion of fish consumed increasing with tripletail length. On the basis of the results of this study as well as previous research on the life history and population dynamics of tripletail, the state of Alabama implemented a 406 mm (16 inch) minimum size limit for this species. This size limit is below the female size at 50% maturity (19.5-23.5 inch) and should be increased if large increases in fishing pressure occur

Resilience of a Commercial Fishing Fleet Following Emergency Closures in the Gulf of Mexico

We used high-resolution fisheries-dependent data and a quantitative modeling approach to examine resilience of a commercial reef fish fleet after the Deepwater Horizon oil spill (DWH) emergency closures in 2010. Our results indicate that the fleet was largely resilient to the closures, although there were spatially-varying differences in attrition, and concomitant management changes and emergency payouts that likely influenced resilience. Five percent of previously active vessels exited the fleet after DWH (compared to the background annual attrition rate of ˜20%). The predicted probability of exiting after DWH was lower for vessels with a pre-closure history of high catch-per-unit-effort, low snapper revenue variability, or low grouper revenue. There was ˜80% overlap in pre- to post-DWH effort distribution, although vessels that exited concentrated effort in the north-central and eastern Gulf of Mexico. The Vessels of Opportunity program and other emergency compensation likely ameliorated some of the negative economic impacts from DWH, allowing more vessels to remain in the fleet than may have otherwise. Implementation of gear restrictions and individual fishing quotas leading up to DWH may have also ‘primed’ the fleet for resilience by removing marginal fishers. This work is novel in its use of high-resolution spatial data, coupled with trip logbooks, to construct quantitative models identifying drivers of fisher resilience after significant and sudden perturbations to fishery resources in the Gulf of Mexico. This work also highlights the need to better understand fisher response to disturbance for long-term fishery sustainability and management

Disturbance modifies payoffs in the explore-exploit trade-off

AbstractDecision-making agents face a fundamental trade-off between exploring new opportunities with risky outcomes versus exploiting familiar options with more certain but potentially suboptimal outcomes. Although mediation of this trade-off is essential to adaptive behavior and has for decades been assumed to modulate performance, the empirical consequences of human exploratory strategies are unknown beyond laboratory or theoretical settings. Leveraging 540,000 vessel position records from 2494 commercial fishing trips along with corresponding revenues, here we find that during undisturbed conditions, there was no relationship between exploration and performance, contrary to theoretical predictions. However, during a major disturbance event which closed the most-utilized fishing grounds, explorers benefited significantly from less-impacted revenues and were also more likely to continue fishing. We conclude that in stochastic natural systems characterized by non-stationary rewards, the role of exploration in buffering against disturbance may be greater than previously thought in humans.</jats:p

Disturbance Modifies Payoffs in the Explore-exploit Trade-off

Decision-making agents face a fundamental trade-off between exploring new opportunities with risky outcomes versus exploiting familiar options with more certain but potentially suboptimal outcomes. Although mediation of this trade-off is essential to adaptive behavior and has for decades been assumed to modulate performance, the empirical consequences of human exploratory strategies are unknown beyond laboratory or theoretical settings. Leveraging 540,000 vessel position records from 2494 commercial fishing trips along with corresponding revenues, here we find that during undisturbed conditions, there was no relationship between exploration and performance, contrary to theoretical predictions. However, during a major disturbance event which closed the most-utilized fishing grounds, explorers benefited significantly from less-impacted revenues and were also more likely to continue fishing. We conclude that in stochastic natural systems characterized by non-stationary rewards, the role of exploration in buffering against disturbance may be greater than previously thought in humans. The empirical consequences of human explorative strategies are not fully understood. Here the authors find that during undisturbed conditions, more-explorative vessels gained no performance advantage while during a major disturbance event, explorers benefited significantly from less-impacted revenues and were also more likely to continue fishing