Human and environmental gradients predict catch, effort, and species composition in a large Micronesian coral-reef fishery

Abstract

The consistent supply of fresh fish to commercial markets may mask growing fishing footprints and localized depletions, as fishing expands to deeper/further reefs, smaller fish, and more resilient species. To test this hypothesis, species-based records and fisher interviews were gathered over one year within a large, demand-driven coral-reef fishery in Chuuk, Micronesia. We first assessed catch statistics with respect to high windspeeds and moon phases that are known to constrain both catch and effort. While lower daily catch success was predicted by higher windspeeds and greater lunar illumination, total daily landings fluctuated less than fishing success across environmental gradients. Instead, daily landings were mainly driven by the number of flights from Chuuk to Guam (i.e., international demand). Given that demand masked local drivers of overall catch volume, we further evaluated species-based indicators of fisheries exploitation. Most target species (75%) had either a positively skewed size distribution or proportional contributions that were dependent upon favorable conditions (i.e. season and moon phases). Skewed size distributions indicated truncated growth associated with fishing mortality, and in turn, suggested that size-based management policies may be most effective for these species. In contrast, environmentally-constrained catch success indicated species that may be more susceptible to growing fishing footprints and may respond better to gear/quota/area policies compared to size policies. Species-based responses offered a simplified means to combine species into fisheries management units. Finally, a comparison of commercial and subsistence landings showed higher vulnerability to fishing among species preferentially targeted by commercial fisheries, offering new insights into how commercial harvesting can disproportionately impact resources, despite having lower annual catch volumes.

Co-evolution of “race-to-fish” dynamics and declining size structures in an expanding commercial coral-reef fishery

“…These species may have a comparatively strong density-dependent responses making them more resilient to fishing pressure. Previous studies have shown their consistent contributions to overall landings despite size-structure shifts (Taylor et al 2014b;Cuetos-Bueno et al 2018;Houk et al 2018b). Similarly, larger sizes of rudderfish, K. cinerascens, and goatfish, M. flavolineatus, found on the more populated island of Saipan compared to Rota and Tinian are consistent with a temporal study on Guam showing these species became more prolific with increasing fishing pressure over a 20 years period (Houk et al 2018b).…”

“…The present results offered that variability can also arise from environmental cycles that dictate access to more remote locations. As a result, fisheries expansions can mask localized depletions that are not recorded in most historical landings datasets (Crona et al 2016;Cuetos-Bueno et al 2018). We conclude that examining even coarse monthly landing records through time with respect to environmental regimes can provide one indication of localized depletions that corresponded with size-and-age structure shifts and are desirable for further research.…”

“…We next examined NAP datasets to explore historical trends in landings with respect to windspeed, rainfall, and season. Windspeeds represent a significant environmental factor predicting fish landings in CNMI, and across Micronesia because high winds and wave limit fishing access (Houk et al 2012Taylor et al 2014a;Cuetos-Bueno et al 2018). In contrast, previous studies have shown a weaker or non-significant contribution of rainfall which was also examined here.…”

Standing Out in a Big Crowd: High Cultural and Economic Value of Naso unicornis in the Insular Pacific

“…These criteria yielded seven data sets that have been summarized in the peer-reviewed or grey literature, mostly stemming from the Micronesian region and within the United States-affiliated islands and the Federated States of Micronesia (FSM). These included long-term (>1 year) commercial fishery surveys from Guam (methods provided in [22]), Saipan (Commonwealth of the Mariana Islands) [11], Tutuila (American Samoa; methods provided in [22]), Pohnpei (FSM) [4,12], Chuuk (FSM) [14], and Kosrae (FSM) [15]. I accessed State of Hawaii fishery market surveys (which summarize commercial landings in the Main Hawaiian Islands) from the Hawaii Division of Aquatic Resources Commercial Marine Landings for the period 2010 to 2015.…”

Length‐Based Assessment of an Artisanal Albulid Fishery in the South Pacific: a Data‐Limited Approach for Management and Conservation

“…Many of the most severe fisheries declines are in data-deficient artisanal fisheries (Pauly 1997;Allison and Ellis 2001;Neil et al 2007;Worm et al 2009;Johnson et al 2013), where communities lack the capacity to conduct research and monitor the status of their yields and where robust governance structures or formal monitoring programs are absent (Hughes et al 2010;Fenner 2012). This paradigm is universal in the artisanal fisheries of the tropical Pacific Ocean, where low fish biomass and altered reef ecosystems are associated with human inhabitation (Friedlander and DeMartini 2002;DeMartini et al 2008;Sandin et al 2008), and there is an urgent need to manage these fisheries on local and regional scales (Bell et al 2009;Houk et al 2012Houk et al , 2017Houk et al , 2018Cuetos-Bueno et al 2018).…”