An applied framework to assess exploitation and guide management of coral‐reef fisheries

Abstract

Abstract. Coral-reef fisheries pose a problem for traditional forms of management because stock assessments and demographic data are limited in diverse systems. We used catch records coupled with fisher interviews to derive hierarchical indicators of fishery status by (1) characterizing catch-and-effort trends with respect to environmental factors, (2) assessing the degree to which biomass-and-abundance distributions were coupled across trophic levels, and (3) identifying key characteristics of species-based landings that were sensitive to fishing pressure and linked with management guidance. Using data across one year from a representative Pacific Island fishery, we show that catch and effort were constrained by environments, as both were disproportionally highest during favorable new moon phases in spring, but more effort was required to catch fewer fish later in the year, and the size of target species declined. The magnitude of constrained catch success provided an initial indication of status that could be compared spatially and temporally. Second, biomass-and-abundance distributions were examined within dominant fish families. Large-bodied species contributed most to biomass in low trophic positions, but small-bodied counterparts were more abundant, following expected observations from systems with less human influence. However, biomass-and-abundance distributions became coupled for invertivores and predators, as small species and individuals were most represented. The shape and fit of regressions between asymptotic lengths and proportional landings identified drivers of coupled distributions. Polynomial fits highlighted that smaller-bodied species were main components of the fishery, while linear fits suggested that largerbodied species were still dominant, and tolerant of current fishing pressure. Last, two indicators were used to identify management objectives for target fishes, skewness of size distributions and proportional contributions to landings. Significantly skewed size distributions existed for most target fishes, suggesting high density dependence and recruitment, and the potential for size-based polices to achieve desirable fishery objectives. Meanwhile, the diminished and constrained contribution of many large species indicated their vulnerability despite non-significant shifts in size. Catch quotas, gear limitations, or temporary restrictions may be more appropriate for sustaining these species. A framework is synthesized to interact with stakeholders and consider holistic management approaches for multispecies coral-reef fisheries.

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.…”

“…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. An unpublished data set from Palau (Houk and Cuetos-Bueno, unpublished data; collected over a one-year period spanning 2017) followed protocols from Cuetos-Bueno et al [14] and Houk et al [15]. Finally, I included a fishery market survey from Yap [13] that spanned only six months but had a high-frequency of sampling (nearly 75% of days surveyed).…”

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

“…Eventually, growing variability is expected to amplify seasonal peaks in landings, such as improved catches at the onset of calm months when many target species are most susceptible, or improved catches during spawning seasons (Claro et al 2009;Hernandez-Ortiz et al 2016;Houk et al 2017). Within, we equate this to ''race-to-fish'' dynamics, as improved catch success and landings become concentrated at the start of a favorable timeframe or season, but rapidly decline to reference levels afterwards (Sys et al 2017).…”

“…Compensatory density dependence dictates that target species should shift in size structure with fishing pressure, as landings of large fish are increasingly being replaced by smaller and younger fish (Jennings et al 1999;Shin et al 2005). Species replacements can also occur as larger, slower-growing preferred target species become replaced by more resilient and less preferred counterparts that have stronger density dependence (Pauly et al 1998;Kaunda-Arara et al 2003;Houk et al 2017). Both species replacement and size-structure changes have been suggested as useful indicators of changing stock status (Shin et al 2005;Houk et al 2017), and diminishing size-and-age structures form the basis for widely used fisheries management models that derive fishing-versus-natural mortality and spawning potential ratios (Nadon et al 2015;Prince et al 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).…”