Mendez-Jimenez A.,Texas A&M University |
Heyman W.D.,LGL Ecological Research Associates Inc. |
Dimarco S.F.,Texas A&M University
Physical Geography | Year: 2015
Most commercially, important food fishes in the tropics reproduce in spawning aggregations, which serve to replenish their populations via larval dispersal. Dispersal pathways are not well understood. This study examines the dispersal hypothesis assumed for most dispersal modeling studies, i.e. that prevailing currents transport freshly released eggs offshore and away from spawning sites, where they are advected into far-field ocean currents and contribute to long-distance larval transport. We used GPS-tracked surface drifters, quantitative ichthyoplankton tows, and microsatellite DNA markers to assess egg dispersal pathways from a well-documented Lutjanus cyanopterus spawning aggregation site. We conducted and plotted 95 drifter tracks over a bathymetric map of the study area and used geoprocessing techniques to determine the direction, speed, and variability of these tracks. Our field-collected data do not support the hypothesis that surface currents transport Cubera snapper gametes offshore during peak spawning. Eggs were transported onshore toward the barrier reef and potentially through the channel, supporting the idea that local retention may be more important than long-distance transport. These results are highly relevant for parameterizing larval connectivity models. Furthermore, we demonstrate the use of a low-cost and easily replicable method to track currents and egg dispersal from spawning aggregation sites. © 2015 Taylor & Francis.
Granados-Dieseldorff P.,Texas A&M University |
Heyman W.D.,Texas A&M University |
Azueta J.,LGL Ecological Research Associates Inc.
Fisheries Research | Year: 2013
Since the 1950s, artisanal fishers from southern Belize have harvested mutton snapper (Lutjanus analis) from the Gladden Spit fish spawning aggregation site. In 2000, the Government of Belize partnered with stakeholders to conserve the area and co-manage the fishery. The objective of this study was to present the history of the artisanal mutton snapper fishery in its environmental and socioeconomic context and qualitatively evaluate its present status. We identified long-term trends in the fishing activity through historical catch reconstructions and estimation of fishing fleet size since the late 1980s, statistically compared inter-annual trends in catch per unit effort (CPUE) and in mutton snapper sizes between 1999 and 2011, and delineated possible factors that might have caused the observed patterns. Our data show a sharp reduction in total landings and fishing effort that started in the late 1980s, parallel to a rapid growth in the tourism industry and to a shift in the livelihoods of many fishers. Annual CPUE, individual sizes, and sex ratios have been relatively stable between 1999 and 2011, indicating persistence of the fishery during this recent period. Key to successful long-term, adaptive co-management of the fishery is a continued involvement of fishers and other stakeholders in resource monitoring and evaluation, as well as in policy and decision making. © 2013 Elsevier B.V.
Carr L.M.,Texas A&M University |
Heyman W.D.,LGL Ecological Research Associates Inc.
Marine Policy | Year: 2016
This research develops a methodology to evaluate public support for fishing regulations, comparing existing regulations designed without much public input, to possible alternative regulations based fishers' ecological knowledge (FEK) and preferences. First, a survey and open-ended interview was completed with 42 fishers in St. Croix, U.S. Virgin Islands (33% of the total number of currently registered commercial fishers on island) regarding general matters of fishery health and productivity, with heightened focus on the management of a mutton snapper (Lutjanus analis) spawning aggregation. The interview results suggest that fishers view management tools in terms of spatial and temporal parameters, and how much those regulations influence gear selection. Fishers respond primarily to socioeconomic pressures, but recognize and support ecological goals of regulations, particularly those that provide protections to important stocks throughout their spawning season. A Discrete Choice Model (DCM) was developed based on the results of the fisher surveys and was administered to 182 individuals, including 54 residents of St. Croix and all 42 fishers interviewed. Eight DCM options were presented to respondents who selected their regulatory preference in a pair-wise fashion. In seven of eight pairs, public respondents selected fisher-preferred, FEK-based regulatory frameworks. These results suggest FEK can be used to develop fishery regulations that will meet management goals, and be broadly supported by both members of the fishing community and the general public. In this manner, ecosystem-based management frameworks can be improved by incorporating fishers and their FEK, particularly for small-scale fisheries. © 2016 Elsevier Ltd.
Carr L.M.,LGL Ecological Research Associates Inc. |
Heyman W.D.,LGL Ecological Research Associates Inc.
Ecological Economics | Year: 2014
This paper examines how fishers' ecological knowledge (FEK) and the analysis of their decision-making process can be used to help managers anticipate fisher behavior and thus be able to efficiently allocate scarce resources for monitoring and enforcement. To examine determinants of fisher behaviors, this study develops a coupled behavior-economic model examining how physical, market, and regulatory forces affect commercial fishers' choice of fishing grounds in a small-scale fishery (SSF) in St. Croix, U.S. Virgin Islands. The model estimates that fishing operations land $396 ± 110 per trip (mean ± 1 SD; n = 427 trips), with the highest value in landings arriving from Lang Bank. The model explains 62% of the variation in fishers' choice to fish at Lang Bank, the most productive, yet farthest fishing grounds. The coupled behavioral-economic model is focused on the small temporal and spatial scales of fishing effort and FEK in an SSF. Therefore the model can be used to predict how a range of physical and regulatory conditions and changes in demand will drive overall (fleet) fishing effort allocation in space and time. By illustrating and quantifying these social-ecological causes and effects, the model can assist managers to efficiently allocate limited monitoring and enforcement resources. © 2014 Elsevier B.V.
Norcross B.L.,University of Alaska Fairbanks |
Raborn S.W.,LGL Ecological Research Associates Inc. |
Holladay B.A.,University of Alaska Fairbanks |
Gallaway B.J.,LGL Ecological Research Associates Inc. |
And 4 more authors.
Continental Shelf Research | Year: 2013
Three closely-spaced study areas in the northeastern Chukchi Sea off of Alaska provided a opportunity to examine demersal fish communities over a small spatial scale as part of a multidisciplinary program. During 2009 and 2010, fishes in the three study areas (Klondike, Burger, and Statoil) were sampled at 37 stations with a plumb staff beam trawl and a 3. m beam trawl; 70% of stations were sampled during all three cruises. Fish catches were dominated by small fishes (<150. mm TL), which cannot be wholly attributed to the small mesh size of the net. Output from generalized linear modeling of the data suggested that overall fish density, species richness, and density of Arctic staghorn sculpin (Gymnocanthus tricuspis) and Bering flounder (Hippoglossoides robustus) were higher in the more southerly Klondike study area than in the more northerly Burger and Statoil study areas. Arctic cod (Boreogadus saida) was abundant throughout the study region. Richness and density could be explained by the environmental variables that defined the overall study area. The Klondike study area was warmer and erosional in nature with higher proportions of gravel sediment. Other study areas were colder and more depositional in nature with muddier sediment and were characterized by high densities of megafaunal invertebrates such as brittle stars. There appeared to be a lack of ecological homogeneity across these three closely-spaced study areas of the Chukchi Sea. © 2013 Elsevier Ltd.