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Rhodes K.L.,University of Hawaii at Hilo | Nemeth R.S.,St. Thomas University at Miami Gardens | Kadison E.,St. Thomas University at Miami Gardens | Joseph E.,Conservation Society of Pohnpei
Coral Reefs | Year: 2014

Long-term and short-term underwater visual censuses using SCUBA, technical Nitrox, and closed circuit rebreathers (CCR) were carried out in Pohnpei, Micronesia, to define spatial and temporal dynamics within a semi-protected multi-species epinephelid (fish) spawning aggregation (FSA) of brown-marbled grouper, Epinephelus fuscoguttatus, camouflage grouper, Epinephelus polyphekadion, and squaretail coralgrouper, Plectropomus areolatus. Results identified species-specific patterns of habitat use, abundance, residency, and dispersal of FSAs. Fish spawning aggregations formed and dispersed monthly within a 21-160-d period after winter solstice within adjacent yet distinct outer reef habitats. The reproductive season coincided with periods of seasonally low sub-surface seawater temperature. Peaks in density varied among species both within the calendar year and relative to the winter solstice. Significant long-term declines in FSA density were observed for all three species, suggesting population-level fishery-induced impacts, similar to those previously reported for E. polyphekadion. Differences in density estimates were also observed between dive gear, with a threefold difference in densities measured by CCR for E. polyphekadion versus SCUBA that suggest a disturbance effect from exhaled SCUBA bubbles for this species. CCR also allowed surveys to be conducted over a larger area in a single dive, thereby improving the potential to gauge actual abundance and density within FSAs. Based on these findings, a combination of long-term and intensive short-term monitoring strategies is recommended to fully characterize trends in seasonal abundance and habitat use for aggregating species at single or multi-species FSA sites. Inherent variations in the timing and distribution of species within FSA make fine-scale temporal management protocols less effective than blanket protective coverage of these species at (e.g., marine protected areas covering FSAs and adjacent migratory corridors) and away from (i.e., temporal sales and catch restrictions) FSA sites. © 2014 Springer-Verlag Berlin Heidelberg. Source

Rhodes K.L.,University of Hawaii at Hilo | McIlwain J.,University of Guam | Joseph E.,Conservation Society of Pohnpei | Nemeth R.S.,St. Thomas University at Miami Gardens
Coral Reefs | Year: 2012

The brown-marbled grouper, Epinephelus fuscoguttatus, is a long-lived, late-maturing protogynous species listed as Near Threatened by the IUCN. In Pohnpei, Micronesia, reproductively active brown-marbled grouper were tagged with acoustic and spaghetti-type tags at a multi-species fish spawning aggregation (FSA) site to establish patterns of movement, residency and seasonality. Telemetry confirmed the use of common reproductive migratory corridors and significant sex-specific variations in residency at the FSA. Combined underwater visual census and telemetry data verified a 3-month peak aggregation period, with aggregations forming and persisting over ca. 12 days prior to full moon between January and May. FSA formation coincided with seasonally low and relatively stable seawater temperatures. Some males frequented the FSA site during each aggregation month over two consecutive years. Conversely, most females were present at the FSA during only a single aggregation period, with the month of visitation consistent among years. Nearly two-thirds of tagged fish were relocated or recaptured within 11 km of the aggregation site, with a maximum detected distance of 26 km and a minimum estimated catchment area of 100-175 km 2. Findings highlight the need for a combined approach to management that prohibits the capture and sale of reproductive adults and protects both spawning sites and common reproductive migratory corridors during aggregation periods. © 2012 Springer-Verlag. Source

Rhodes K.L.,University of Hawaii at Hilo | Taylor B.M.,University of Guam | Taylor B.M.,James Cook University | Joseph E.,Conservation Society of Pohnpei | And 2 more authors.
Journal of Fish Biology | Year: 2013

The squaretail coralgrouper Plectropomus areolatus was identified as a fast-growing, early maturing and relatively short-lived aggregation-spawning epinephelid. Examinations of sectioned otoliths found females and males first maturing at 2 and 3years, respectively, suggesting protogynous hermaphroditism; however, no transitionals were observed in samples. Age distribution for the two sexes was similar and both were represented in the oldest age class; however, significant sex-specific differences in size-at-age were identified. Both sexes fully recruit into the fishery at age 4years and reach 90% of asymptotic length by age 3years. Underwater visual assessments, combined with the gonado-somatic indices, revealed a 5month reproductive season, with interannual variability observed in the month of highest density within the spawning aggregation. Catch restrictions on adults during spawning times and at reproductive sites, combined with gear-based management and enhanced enforcement, are recommended to maintain spawning stocks. Based on the available evidence, the sexual pattern for this species is unresolved. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles. Source

Montambault J.R.,The Nature Conservancy | Wongbusarakum S.,University of Hawaii at Manoa | Wongbusarakum S.,National Oceanic and Atmospheric Administration | Leberer T.,The Nature Conservancy | And 10 more authors.
Conservation Biology | Year: 2015

Adaptive management implies a continuous knowledge-based decision-making process in conservation. Yet, the coupling of scientific monitoring and management frameworks remains rare in practice because formal and informal communication pathways are lacking. We examined 4 cases in Micronesia where conservation practitioners are using new knowledge in the form of monitoring data to advance marine conservation. These cases were drawn from projects in Micronesia Challenge jurisdictions that received funding for coupled monitoring-to-management frameworks and encompassed all segments of adaptive management. Monitoring in Helen Reef, Republic of Palau, was catalyzed by coral bleaching and revealed evidence of overfishing that led to increased enforcement and outreach. In Nimpal Channel, Yap, Federated States of Micronesia (FSM), monitoring the recovery of marine food resources after customary restrictions were put in place led to new, more effective enforcement approaches. Monitoring in Laolao Bay, Saipan, Commonwealth of the Northern Mariana Islands, was catalyzed by observable sediment loads from poor land-use practices and resulted in actions that reduced land-based threats, particularly littering and illegal burning, and revealed additional threats from overfishing. Pohnpei (FSM) began monitoring after observed declines in grouper spawning aggregations. This data led to adjusting marine conservation area boundaries and implementing market-based size class restrictions. Two themes emerged from these cases. First, in each case monitoring was conducted in a manner relevant to the social and ecological systems and integrated into the decision-making process. Second, conservation practitioners and scientists in these cases integrated culturally appropriate stakeholder engagement throughout all phases of the adaptive management cycle. More broadly, our study suggests, when describing adaptive management, providing more details on how monitoring and management activities are linked at similar spatial scales and across similar time frames can enhance the application of knowledge. © 2015, Society for Conservation Biology. Source

Rhodes K.L.,University of Hawaii at Hilo | Warren-Rhodes K.A.,NASA | Sweet S.,TerraUnda | Helgenberger M.,Office of Fisheries and Aquaculture | And 3 more authors.
Environmental Conservation | Year: 2015

Throughout the tropics, developing countries and territories are highly dependent on nearshore marine resources for food and income, however information on the sustainability and proper management of these fisheries is lacking. In Pohnpei, Micronesia, the sustainability of a coral reef finfishery was assessed by comparing coral reef fish demand to coral reef biocapacity using a marine ecological footprint (MEF) analysis. Based on geo-referenced satellite and aerial imagery, Pohnpei and surrounding atolls have 184.2 km2 of coral reef habitat with a sustainable finfish yield of 573-1118 t yr-1, however total harvest was estimated at 4068 t yr-1, exceeding biocapacity by 360-710%. The MEF was supported by observed impacts to coral reef resources, including (1) long-term declines in fish spawning aggregation density, (2) reductions in mean size, age and fecundity of key commercial species, (3) reliance on undersized fish, and (4) decadal declines in mean size and abundance of fishes of iconic value and critical to ecosystem maintenance. The commercial fishery was responsible for 68% of finfish catch volume, while reef fish consumption, at 93 kg person-1 yr-1, was among the highest in the region. To sustainably meet current demand, up to 833 km2 of additional reef area would be required. The study illustrates the MEF, at least rudimentarily, reflects biological reality on local reefs and represents a valuable analytical tool in a marine policymaker's toolbox. © 2014 Foundation for Environmental Conservation. Source

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