Experimental evaluation of the use of hatchery-reared juveniles to enhance stocks of the topshell Trochus niloticus in Australia, Indonesia and Vanuatu

Crowe, Tasman P.; Lee, Chan Lui; McGuinness, Keith A.; Amos, M.; Dangeubun, J.; Dwiono, Sigit Anggoro Putro; Makatipu, Petrus Christianus; Manuputty, Jan; Nguyen, Felix; Pakoa, K.; Tetelepta, J M S

doi:10.1016/s0044-8486(01)00676-7

Cited by 19 publications

(20 citation statements)

References 22 publications

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“…The enhancement of grazing gastropod (trochus) populations has the potential of enhancing the recovery of degraded reef areas through algal grazing and subsequent increase in coral recruitment rate, though technical hurdles in this restoration approach, e.g., predation on restocked individuals, have yet to be addressed (Villanueva et al 2010). In trochus stock enhancement experiments which were not specifically for coral reef restoration, low survival rates were also recorded and improved approaches in restocking have been suggested (Crowe et al 2002;Purcell and Cheng 2010). Rapid recruitment of corals on concrete structures to culture trochus has been documented and hypothesized to be due to the grazing effect of trochus creating suitable substrate for coral recruitment (Omori et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of cultured coral spat

2013

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Background: The technology in the production of sexual coral propagules for coral reef restoration is being actively developed recently to address concerns on the low genetic diversity in coral populations restored through transplantation of coral materials derived from fragmentation. Results: In this study, we produced coral spat attached to rubble and determined the effect of the addition of hatchery-reared trochus, a herbivorous gastropod, at two densities (one and two trochus per cage, equivalent to four and eight trochus per square meter, respectively) on the survivorship of the spat cultured in cages at the hatchery and in situ nursery. After 5 weeks of culture in the hatchery, spat survivorship was significantly higher in the two per cage trochus treatment (18.3% ± 6.7%, mean ± sd) than in the control (5.5% ± 1.7%), with the one per cage trochus treatment having intermediate spat survival (12.6% ± 7.9%). The enhanced spat survivorship, though not apparent in the in situ nursery culture, is attributed to the grazing effect of trochus as significantly lower turf algal cover was observed in rubble placed in two per cage trochus treatment (44.8% ± 3.2%) than in the one per cage trochus treatment and control (80.2% ± 6.5% and 76.3% ± 5.0%, respectively). Conclusions: This study demonstrates that trochus can be used to control algal cover and enhance survivorship of coral spat in caged culture, at least in the hatchery, for the production of sexually derived transplant materials for coral reef restoration.

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Section: Discussionmentioning

confidence: 99%

Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of cultured coral spat

2013

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“…However, because quantitative studies of enhancement efforts are relatively new, though very much needed (e.g., Bannister et al 1994;Heppell and Crowder 1998;Leber 1999;Crowe et al 2002), objective It has been suggested that the ultimate test of enhancement success lies in determining whether a hatchery is economically sustainable (Hilborn 1998), which, in turn, is measured by calculating the number and value of hatchery individuals appearing in the fishery. However, many benefits of enhancement, other than increased fishery catch, are difficult to judge in an economic context.…”

Section: Difficulty In Judging Successmentioning

confidence: 99%

“…However, many benefits of enhancement, other than increased fishery catch, are difficult to judge in an economic context. In particular, enhancement programs may result in improvement of the reproductive output of a population by way of hatchery individuals surviving to maturity (Crowe et al 2002). Therefore, while the economic value of a landed hatcheryproduced mature female can be easily calculated, the unlanded hatchery-produced mature female, which is the goal of this program, may have a much amplified value through the spawning stock -recruitment relationship (Bannister et al 1994;Bannister and Addison 1998;Crowe et al 2002).…”

Section: Difficulty In Judging Successmentioning

confidence: 99%

“…Finally, increases in stock size due to hatchery successes may provoke a rise in fishing effort, and therefore greater pressure on the remaining wild individuals (Hilborn 1998;Bannister 2000). The controversy is fueled by the fact that most enhancement efforts, which date from at least a century ago, have not been studied in a quantitative manner (Bannister et al 1994;Heppell and Crowder 1998;Crowe et al 2002). Such study did not begin until the late 1980s (Leber 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Advances in tools such as tagging have allowed better assessment of survivorship of both hatchery-raised and wild animals (Blackenship and Leber 1995). Most importantly, calls have been made for quantitative study of small-scale enhancement efforts before investment in large-scale programs begins (Leber 1999;Crowe et al 2002). To date, such studies have concentrated on finfishes, as this group is the focus of most enhancement efforts (Secor and Houde 1998;Thorpe 1998;Wilson et al 1998).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the potential for stock enhancement in the case of the Chesapeake Bay blue crab (Callinectes sapidus)

Davis¹,

Young-Williams²,

Hines³

et al. 2005

Can. J. Fish. Aquat. Sci.

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Abstract:In certain cases of severely depleted fishery stocks, combining stock enhancement with traditional management techniques may be a useful way of returning stocks to an exploitable size. The Chesapeake Bay stock of blue crabs (Callinectes sapidus) has declined over the past decade and appears to be recruitment-limited, making it an appropriate candidate for enhancement efforts. This study serves as a first step in determining whether large-scale enhancement of blue crab stocks is feasible. Four hatchery-raised cohorts of 4000 -10 000 (25 000 in total) juvenile (6-30 mm carapace width, 58-70 days old) crabs were released in upper Chesapeake Bay coves. Sixty days after release, these crabs constituted 22%-79% of all crabs in the hatchery-crab size range (corresponding to an enhancement level of 28%-366%). Crabs released earlier in the summer reached maturity at the age of 6 months, younger than their wild counterparts. Estimated survivorship to maturity was 16%-20% for early-released crabs and 5-15% for latereleased crabs. Late-released crabs, like wild crabs, had to overwinter before becoming mature. Our study suggests ways to improve success of hatchery-raised individuals that can be broadly applied across taxa. The results also contribute specifically to determining whether large-scale stock enhancement is possible in the case of the Chesapeake Bay blue crab.Résumé : Chez certains stocks fortement réduits, la combinaison de mesures d'amélioration des stocks et de méthodes de gestion courantes peut être utile pour rétablir les stock à une taille exploitable. Le stock de crabes bleus (Callinectes sapidus) de la baie de Chesapeake a décliné au cours de la dernière décennie et semble limité par des problèmes de recrutement; c'est donc un bon candidat pour les efforts d'amélioration des stocks. Notre étude constitue une première étape pour déterminer si une amélioration du stock de C. sapidus à grande échelle est possible. Quatre cohortes de 4 000 à 10 000 (total de 25 000) jeunes (largeur de carapace, 6-30 mm; âge, 58-70 jours) crabes de culture ont été relâchés dans les anses supérieures de la baie de Chesapeake. Soixante jours après l'ensemencement, ces crabes représentaient 22-79 % des tous les crabes des classes de taille des crabes de culture, ce qui correspond à un niveau d'amélioration de 28-366 %. Les crabes relâchés plus tôt au printemps atteignent la maturité à l'âge de 6 mois, donc plus rapidement que les crabes sauvages. La survie à la maturité est estimée à 16-20 % chez les crabes relâchés tôt et à 5-15 % chez les crabes relâchés tard. Les crabes relâchés tard, tout comme les crabes sauvages, doivent passer l'hiver avant d'atteindre la maturité. Notre étude suggère des méthodes pour augmenter le succès d'individus élevés en culture qui sont largement applicables à d'autres taxons. Nos résultats contribuent aussi de façon spécifique à évaluer si des améliorations de stock à grande échelle sont possibles chez le crabe bleu de la baie de Chesapeake.[Traduit par la Rédaction] Davis et al. 122

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Marine Stock Enhancement Techniques

Davis

2004

Water Encyclopedia

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The United Nations estimates that as many as 75% of the world's fishery stocks are fully exploited, severely depleted, or overexploited and are therefore not eligible for further exploitation to meet growing demands for fishery products. Due to the pressure on fishery populations, several management techniques have been developed. Traditional fishery management seeks to limit the catch of wild fishery stocks. Aquaculture activities, increasing in number, aim to raise aquatic food organisms in captivity. Stock enhancement techniques have been developed to bolster population sizes in the wild, either by providing habitat for habitat‐limited populations or by providing hatchery‐raised juveniles for recruitment‐limited populations. The latter form of stock enhancement has been controversial for a variety of reasons, including viability and health of hatchery‐raised organisms. In addition, success of stock enhancement efforts is often difficult to quantify. Evaluation of this management technique requires laborious efforts to follow hatchery‐raised organisms over time and develop knowledge about wild con‐specifics. Despite the controversy and difficulty in assessing the success of stock enhancement programs, stock enhancement may be a required step in the management of species or stocks that are extremely depleted.

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Experimental evaluation of the use of hatchery-reared juveniles to enhance stocks of the topshell Trochus niloticus in Australia, Indonesia and Vanuatu

Cited by 19 publications

References 22 publications

Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of cultured coral spat

Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of cultured coral spat

Assessing the potential for stock enhancement in the case of the Chesapeake Bay blue crab (Callinectes sapidus)

Marine Stock Enhancement Techniques

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