Life histories predict vulnerability to overexploitation in parrotfishes

Taylor, Brett M.; Houk, Peter; Russ, Garry R.; Choat, J. Howard

doi:10.1007/s00338-014-1187-5

Cited by 79 publications

(73 citation statements)

References 45 publications

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“…Aside from these quality and data availability issues, we find almost without exception that previous tests of life-history trait relationships with population trajectories while accounting for fishing mortality occurred within fish assemblages and were all conducted at local scales either in the European shelf seas [20,21,45] or the Pacific coral reefs [12,19,46]. Hence, within a single and relative homogeneous environment, maximum body size may be sufficient to rank the relative vulnerability of species to fishing exploitation within fish assemblages.…”

Section: Discussionmentioning

confidence: 92%

Population declines of tuna and relatives depend on their speed of life

Juan‐Jordá

Mosqueira²,

Freire³

et al. 2015

Proc. R. Soc. B.

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Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size-and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions.

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Section: Discussionmentioning

confidence: 92%

Population declines of tuna and relatives depend on their speed of life

Juan‐Jordá

Mosqueira²,

Freire³

et al. 2015

Proc. R. Soc. B.

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“…Analogous logistic curves were fitted to proportion TP male across all females and males to produce estimates of body lengths at median sex change ( L Δ50 ). Both L M50 and L Δ50 can be meaningfully related to maximum body length ( L max ), so L M50 and L Δ50 were standardized as a proportion of L max , where the latter was estimated as the mean of the largest quartile of lengths of that species in the collection series (Taylor et al , ). Round mass was related to L F using Proc NLIN, and these estimates of mass at length were then used to convert L M50 and L Δ50 to total body masses at median sexual maturity of females ( M M50 ) and at median sex change of adults ( M Δ50 ), respectively.…”

Section: Methodsmentioning

confidence: 99%

Comparisons of body sizes at sexual maturity and at sex change in the parrotfishes of Hawaii: input needed for management regulations and stock assessments

DeMartini

Howard

2016

Journal of Fish Biology

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First estimates of sex allocation patterns and body size-at-sexual maturity and at protogynous sex change are presented for the five major (including one endemic) species of parrotfishes of Hawaii. Median body size at initial maturation as a female (LM50) and at protogynous sex change from adult female to adult male (LΔ50) varied greatly among the five species. Estimates of LM50 were about 14, 17, 24, 34 and 35 cm fork length (LF) in palenose Scarus psittacus, Pacific bullethead Chlorurus spilurus, stareye Calotomus carolinus, spectacled Chlorurus perspicillatus and redlip parrotfish Scarus rubroviolaceus. Values of LΔ50 were c. 23, 27, 37, 46 and 47 cm LF in the respective species. Length at female maturation was proportional to maximum body size (Lmax) of the respective species, ranging from 50 to 72% and averaging 62% of Lmax across species. LΔ50 was also proportional to Lmax, ranging from 82 to 97% and averaging 92%. Males of both pairs of Scarus and Chlorurus spp. reported here are diandric. Only one of the five major species (C. carolinus) is functionally monandric, with either all or nearly all males secondarily derived from adult females. The broadly differing absolute body sizes at sexual maturation and at sex change among the five species have important implications for improving regulatory size limits for parrotfishes in the State of Hawaii, where parrotfish species have historically been managed based on a single minimum size limit of 30·5 cm LF. This study provides a model demonstration of why catch data for parrotfishes, and other size-structured reef-fish populations, should be recorded either by species or by functional size-groups of species that allow setting more meaningful minimum size limits.

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“…It has been shown that so long as a sufficient spawning stock is maintained, the presence of immature fish in catches does not necessarily signify recruitment overfishing (Mahon and Hunte, 2001). A population may thus be subjected to high fishing mortality at certain life stages of the resources but yet does not show signs of overexploitation (Taylor et al, 2014). A recent theoretical exploration of the effect of the use of small gill nets in tropical fisheries , has shown that large spawners and megaspawners may well be protected, even if fishing pressure is high.…”

Section: Emerging Patterns Of the Multispecies Multigear Fisherymentioning

confidence: 97%