Hazards of managing disparate species as a pooled complex: A general problem illustrated by two contrasting examples from Hawaii

DeMartini, Edward E.

doi:10.1111/faf.12404

Cited by 9 publications

(6 citation statements)

References 64 publications

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“…Ignoring the influences of supplemental recruitment via immigration will overestimate yields and produce inaccurate overestimates. We believe that modelling methods should produce conservative estimates because of the inherent risks, such as species and economic losses, associated with multi‐species model predictions (DeMartini, 2019; Thorpe, 2019; Tromeur & Doyen, 2019).…”

Section: Discussionmentioning

confidence: 99%

Improving sustainable yield estimates for tropical reef fisheries

McClanahan

Azali²

2020

Fish and Fisheries

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Sustainable fishing is one of the main goals of human development but is challenged by a number of fundamental social-ecological and fisheries science problems. These challenges are particularly acute in tropical countries where fisheries information and science currently lack reliable estimates of status and sustainability (Hilborn et al., 2020). For example, fisheries catch statistics suffer from foundational problems of lacking accurate estimates of effort (=E), yield (=Y), catch per unit effort (=CPUE) and areas from which catches come (=CPUA) (Dalzell, 1996;McClanahan, 2018;Pauly & Zeller, 2016). Secondarily, there is the problem of having a time series of consistently collected data that is restricted to specific and stable use of fishing gears, areas and old enough to evaluate the stability of yields. These are among the critical challenges in data-poor locations where robust recommendations are needed to reduce overfishing, poverty and better achieve sustainability goals.

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Section: Discussionmentioning

confidence: 99%

Improving sustainable yield estimates for tropical reef fisheries

McClanahan

Azali²

2020

Fish and Fisheries

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“…However, its congener opakapaka (P. filamentosus) -along with ehu (E. carbunculus) -have more rapid growth with k values on the order of 0.20-0.25 (Andrews et al, 2012;Nichols, 2019). It follows that a species often landed with the Deep 7 fishes, the uku or grey snapper (Aprion virescens), exhibits a rapid growth rate (k ≈ 0.3) that is similar to gindai with a validated lifespan from bomb 14 C dating of 25 years (DeMartini, 2019;Nadon et al, 2020). Hence, the importance of employing age validation techniques, like the unique utility of the bomb 14 C decline period, to authenticate age reading protocols and the estimates of age and growth derived from otolith sections are highlighted here for deep-water snapper in Hawaii and are broadly applicable to tropical marine fishes.…”

Section: Fisheries and Aquatic Sciencesmentioning

confidence: 99%

“…This species does not comprise a large proportion (1%-2% by weight) of the Deep 7 catch in Hawaii (Langseth et al, 2018), but its importance has increased over the recorded history of this fishery (DeMartini, 2019). The age and growth of this spehttps://doi.org/10.47853/FAS.2021.e6…”

Section: Introductionmentioning

confidence: 99%

Early overcounting in otoliths: a case study of age and growth for gindai (Pristipomoides zonatus) using bomb 14C dating

Andrews¹,

Scofield²

2021

Fish Aquat Sci

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Gindai (Pristipomoides zonatus) is one of six snappers in a management complex called the Deep 7 of the Hawaiian Islands. Little is known about its life history and a preliminary analysis of otolith thin sections indicated the species may exhibit moderate growth with a lifespan approaching 40 years. Preliminary age estimates from the previous study were reinvestigated using the same otolith sections in an attempt to validate those ages with bomb radiocarbon (14 C) dating. From the misalignment of birth years for the otolith 14 C measurements with regional references-the post-peak bomb 14 C decline period-it was concluded that previous ages were inflated from overcounting of the earliest growth zone structure in otolith sections. The oldest gindai was re-aged to 26 years once the age reading was adjusted for early overcounting, 13 years younger than the original estimate of 39 years for this fish. In general, the earliest otolith growth of gindai was massive and complicated by numerous subannual checks. The approach of lumping the early growth structures was supported by the alignment of 14 C measurements from otolith core material (first year of growth). The result was greater consistency of calculated birthdates with the 14 C decline reference, along with minor offsets that may indicate age estimation was imprecise by a few years for some individuals. The revised von Bertalanffy growth function applied to the validated age-at-length estimates revealed more rapid growth (k = 0.378 cf. 0.113) and a lifespan of approximately 30 years. The findings presented here are a case study of how the bomb 14 C decline period can be used as a tool in the refinement of age reading protocols.

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“…However, rarely is the full extent of this information available to adequately determine the appropriateness of a complex grouping, and there can be a mismatch in groupings when using life history traits compared to fishery susceptibility (i.e., species caught together by the same gear types). Grouping species based on life history characteristics, which represent the population's productivity, is important because species with similar growth and maturity often demonstrate similar responses to fishing pressure (e.g., Farmer et al, 2016;DeMartini, 2019). From a management perspective, grouping by susceptibility to fishing gear (e.g., multispecies fisheries) is often simpler than grouping by life history traits, because management by gear type is less easily enforceable for complexes harvested by a variety of gears.…”

Section: Introductionmentioning

confidence: 99%

“…From a management perspective, grouping by susceptibility to fishing gear (e.g., multispecies fisheries) is often simpler than grouping by life history traits, because management by gear type is less easily enforceable for complexes harvested by a variety of gears. Yet, the potential for disproportionate impacts on the species within the complex exists when complexes are formed using gear susceptibility and when selectivity or availability differs by species (DeMartini, 2019).…”

Section: Introductionmentioning

confidence: 99%

Methods for Identifying Species Complexes Using a Novel Suite of Multivariate Approaches and Multiple Data Sources: A Case Study With Gulf of Alaska Rockfish

et al. 2021

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International and national laws governing the management of living marine resources generally require specification of harvest limits. To assist with the management of data-limited species, stocks are often grouped into complexes and assessed and managed as a single unit. The species that comprise a complex should have similar life history, susceptibility to the fishing gear, and spatial distribution, such that common management measures will likely lead to sustainable harvest of all species in the complex. However, forming complexes to meet these standards is difficult due to the lack of basic biological or fisheries data to inform estimates of biological vulnerability and fishery susceptibility. A variety of cluster and ordination techniques are applied to bycatch rockfish species in the Gulf of Alaska (GOA) as a case study to demonstrate how groupings may differ based on the multivariate techniques used and the availability and reliability of life history, fishery independent survey, and fishery catch data. For GOA rockfish, our results demonstrate that fishing gear primarily defined differences in species composition, and we suggest that these species be grouped by susceptibility to the main fishing gears while monitoring those species with high vulnerabilities to overfishing. Current GOA rockfish complex delineations (i.e., Other Rockfish and Demersal Shelf Rockfish) are consistent with the results of this study, but should be expanded across the entire GOA. Differences observed across species groupings for the variety of data types and multivariate approaches utilized demonstrate the importance of exploring a diversity of methods. As best practice in identifying species complexes, we suggest using a productivity-susceptibility analysis or expert judgment to begin groupings. Then a variety of multivariate techniques and data sources should be used to identify complexes, while balancing an appropriate number of manageable groups. Thus, optimal species complex groupings should be determined by commonality and consistency among a variety of multivariate methods and datasets.

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Hazards of managing disparate species as a pooled complex: A general problem illustrated by two contrasting examples from Hawaii

Cited by 9 publications

References 64 publications

Improving sustainable yield estimates for tropical reef fisheries

Improving sustainable yield estimates for tropical reef fisheries

Early overcounting in otoliths: a case study of age and growth for gindai (Pristipomoides zonatus) using bomb 14C dating

Methods for Identifying Species Complexes Using a Novel Suite of Multivariate Approaches and Multiple Data Sources: A Case Study With Gulf of Alaska Rockfish

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