Size-specific predation of juvenile queen conch Strombus gigas: implications for stock enhancement

Ray, Melody; Stoner, Allan W.; O’Connell, Sheila M.

doi:10.1016/0044-8486(94)90103-1

Cited by 28 publications

(11 citation statements)

References 13 publications

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“…The mean ratios of the height of the 8th and 9th carapace spines of wild crabs in this study are comparable to ratios reported by Keenan et al (1998) for wild S. serrata, whereas the relative length of the 9th carapace spines of hatchery-reared crabs was significantly shorter than that in wild crabs in both the present study and Keenan et al (1998). Similar observations have been made in the blue crab Callinectes sapidus, where hatchery-produced crabs were found to have smaller lateral carapace spines than wild conspecifics (Davis et al 2004), and in molluscs; both Stoner and Davis (1994) and Ray et al (1994) reported truncated and fewer spines in hatchery-produced queen conch Strombus gigas, when compared to wild specimens. However, the morphological characteristics were found to be plastic in these cases and could be altered by transferring hatchery-produced animals into the natural environment (Stoner and Davis 1994;Ray et al 1994;Davis et al 2004Davis et al , 2005a.…”

Section: Discussionsupporting

confidence: 66%

“…Differences between hatchery-reared and wild invertebrates have recently been reviewed by Le Vay et al (2007) and may include colouration and pigmentation, claw morphology, spine development, shell thickness and behaviour (e.g. Ray et al 1994;Stoner and Davis 1994;Davis et al 2004Davis et al , 2005a. Identifying differences between hatchery-reared and wild organisms allows research to focus upon assessment of their significance and improvement of survivorship through development of appropriate conditioning steps (Young et al 2008).…”

Section: Introductionmentioning

confidence: 98%

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Phenotypic differences between hatchery-reared and wild mud crabs, Scylla Serrata, and the effects of conditioning

2010

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Hatchery-reared animals for stock enhancement should be competent to survive and grow at rates equivalent to those of wild conspecifics. However, morphological differences are often observed, and pre-conditioning steps may be required to improve the fitness of hatchery-reared juveniles prior to release. In the present study, hatchery-reared Scylla serrata juveniles were reared either individually (HR-solitary) or groups in tanks (HR-communal), the latter group being exposed to intraspecific competition and foraging for food. After 21 days, both groups were compared to similar size wild-caught juveniles in terms of morphometric measurements of carapace spination, abnormalities and carapace colouration. There were some limited significant differences between HR-communal crabs and HR-solitary crabs in terms of length of 8th and 9th lateral spines and in body-weightcarapace width ratio, but both treatments differed from wild crabs, which were heavier and had longer carapace spines for their size. In contrast, both HR treatments exhibited common abnormalities including deformities in the shape of the abdomen, in particular occurrence of an asymmetrical telson or a deeply folded telson. In all cases, abnormalities persisted through moulting. Initially, carapace colour differed in all measures of colour between HR and wild crabs. However, these differences reduced after a period of 4-8 days of conditioning on coloured tank backgrounds or dark sand or mud backgrounds, without moulting. Similarly, hatchery-reared crabs exhibited very limited burying behaviour on first exposure to sediment, but this increased to levels observed in wild crabs within 2-4 days. Thus, short-term conditioning of hatchery-reared crabs on dark sediments may be effective in increasing predator avoidance and survivorship in released animals, and present results suggest that this can be achieved after relatively short periods of 1 week or less.

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Section: Discussionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 98%

Phenotypic differences between hatchery-reared and wild mud crabs, Scylla Serrata, and the effects of conditioning

2010

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“…Unlike several other studies for fishes (Bolker and Hill, 2000;Kellison et al, 2000) and invertebrates (Ray et al, 1994;Stoner and Davis, 1994), which found reduced fitness of cultured animals, our tethering experiments revealed few differences in survival of hatchery-reared and wild juveniles. Simultaneous field releases of free-ranging wild and hatchery-reared blue crabs showed that, while juveniles sometimes suffered higher mortality than wild crabs, there were usually no differences in survival.…”

Section: Ultimate Impact On Stock Enhancement Successcontrasting

confidence: 38%

Do Hatchery-Reared Blue Crabs Differ from Wild Crabs, and Does it Matter?

Young

Johnson

Davis

et al. 2008

Reviews in Fisheries Science

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“…Given that the ECLSP population is aging, the cause of decline is likely tied to early life history. A key demographic rate for conch is high juvenile mortality prior to the formation of a larger shell that offers predation relief (Iversen et al 1986, 1990, Ray et al 1994. The ECLSP has one of the densest populations of grouper in the Caribbean (Mumby et al 2011), likely as a result of the effective no-take reserve regulations.…”

Section: Discussionmentioning

confidence: 99%

Efficacy of an established marine protected area at sustaining a queen conch Lobatus gigas population during three decades of monitoring

Kough¹,

Cronin²,

Skubel³

et al. 2017

Mar. Ecol. Prog. Ser.

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Marine Protected Areas (MPAs) are designed to conserve and preserve the ecosystems and cultural resources of the ocean. In theory, protected populations flourish, replenish adjacent regions, and are self-sustaining. However, describing the efficacy of MPAs requires long-term monitoring. Queen conch Lobatus gigas are iconic Caribbean denizens with populations that have been decimated by overfishing and are slow to rebound due to density-dependent breeding. The Exuma Cays Land and Sea Park (ECLSP) is a well-enforced, no-take, old, and large MPA. Surveys in 1994, 2011, and 2016 were used to track changes in the abundance, size, and age structure of conch within the park. Statistical models suggested that abundances of adults in 50 km of repeated towed-observer surveys had declined by 71% in 2016 relative to 2011. Further, the remaining conch populations were associated with tidal channels, and these model results agreed with independent observations in 40 km of expanded survey area. Measurements of shell lip thickness, an estimator of relative age, showed an increase relative to 1994 with the greatest effect in 2016, indicating senescence. The ECLSP population appears to be slowly dying of old age, and an early life history process has been altered. Upstream populations have been heavily fished while habitats within the park remain productive, suggesting that low local retention and a lack of exogenous larval sources are driving the decline. A network of MPAs encompassing the entire life cycle and dispersal envelope of targeted organisms is needed for proper conch conservation. Surveys focused on tidal channels could locate candidate upstream populations of conch.

show abstract

Size-specific predation of juvenile queen conch Strombus gigas: implications for stock enhancement

Cited by 28 publications

References 13 publications

Phenotypic differences between hatchery-reared and wild mud crabs, Scylla Serrata, and the effects of conditioning

Phenotypic differences between hatchery-reared and wild mud crabs, Scylla Serrata, and the effects of conditioning

Do Hatchery-Reared Blue Crabs Differ from Wild Crabs, and Does it Matter?

Efficacy of an established marine protected area at sustaining a queen conch Lobatus gigas population during three decades of monitoring

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