Abstract
Queen conch (Lobatus gigas) is a large herbivorous gastropod, found across the Caribbean, which forms the basis of important dive fisheries. Conch have a two-phase shell growth pattern, first in shell length (SL), which ceases well before maturity, followed by growth in shell lip thickness (LT) into maturity. This growth pattern must be considered in determining the ideal size and associated maturity for sustainable harvest. Shell morphology, sex organ development and soft tissue masses indicated that mature adult conchs at Glover's Atoll, Belize, were those with thick shell lips (≥10 mm), eroded shells and heavier soft tissue masses. Therefore, SL-based regulations cannot serve as a proxy for maturity and harvest. The use of inappropriate minimum size limits (SL = 178 mm, 85 g market clean meat mass) has allowed significant juvenile harvest and the fishery appears to have truncated the SL size distribution of conchs with a flared shell lip (i.e. adults) over the last 15 years. The reduced SL observed in lipped conchs may lead to a significant impact on the reproductive success of the population as well as diminished economic yield from the fishery, as smaller adult conchs of the same age have lower gonad and meat weight. We believe this to be the first documentation of a decline in the SL of adult queen conchs, and that the SL-based size limits have contributed to this decline. Refinement of the individual size-based regulations for conch in Belize to LT will probably facilitate local recovery as well as regional harmonization of regulations. Future research in Belize should include movement dynamics of conch in relation to replenishment zone size and spillover as well as the importance of deep-water conch to shallow-water recruitment, which is thought to be limited.
| Original language | English (US) |
|---|---|
| Journal | Aquatic Conservation: Marine and Freshwater Ecosystems |
| DOIs | |
| State | Published - Jan 1 2019 |
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Keywords
- Belize
- coral reef
- management measures
- overfishing
- queen conch
- seagrass
- small-scale fisheries
ASJC Scopus subject areas
- Aquatic Science
- Ecology
- Nature and Landscape Conservation
Cite this
Declining size of adults and juvenile harvest threatens sustainability of a tropical gastropod, Lobatus gigas, fishery. / Tewfik, Alexander; Babcock, Elizabeth A; Appeldoorn, Richard S.; Gibson, Janet.
In: Aquatic Conservation: Marine and Freshwater Ecosystems, 01.01.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Declining size of adults and juvenile harvest threatens sustainability of a tropical gastropod, Lobatus gigas, fishery
AU - Tewfik, Alexander
AU - Babcock, Elizabeth A
AU - Appeldoorn, Richard S.
AU - Gibson, Janet
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Queen conch (Lobatus gigas) is a large herbivorous gastropod, found across the Caribbean, which forms the basis of important dive fisheries. Conch have a two-phase shell growth pattern, first in shell length (SL), which ceases well before maturity, followed by growth in shell lip thickness (LT) into maturity. This growth pattern must be considered in determining the ideal size and associated maturity for sustainable harvest. Shell morphology, sex organ development and soft tissue masses indicated that mature adult conchs at Glover's Atoll, Belize, were those with thick shell lips (≥10 mm), eroded shells and heavier soft tissue masses. Therefore, SL-based regulations cannot serve as a proxy for maturity and harvest. The use of inappropriate minimum size limits (SL = 178 mm, 85 g market clean meat mass) has allowed significant juvenile harvest and the fishery appears to have truncated the SL size distribution of conchs with a flared shell lip (i.e. adults) over the last 15 years. The reduced SL observed in lipped conchs may lead to a significant impact on the reproductive success of the population as well as diminished economic yield from the fishery, as smaller adult conchs of the same age have lower gonad and meat weight. We believe this to be the first documentation of a decline in the SL of adult queen conchs, and that the SL-based size limits have contributed to this decline. Refinement of the individual size-based regulations for conch in Belize to LT will probably facilitate local recovery as well as regional harmonization of regulations. Future research in Belize should include movement dynamics of conch in relation to replenishment zone size and spillover as well as the importance of deep-water conch to shallow-water recruitment, which is thought to be limited.
AB - Queen conch (Lobatus gigas) is a large herbivorous gastropod, found across the Caribbean, which forms the basis of important dive fisheries. Conch have a two-phase shell growth pattern, first in shell length (SL), which ceases well before maturity, followed by growth in shell lip thickness (LT) into maturity. This growth pattern must be considered in determining the ideal size and associated maturity for sustainable harvest. Shell morphology, sex organ development and soft tissue masses indicated that mature adult conchs at Glover's Atoll, Belize, were those with thick shell lips (≥10 mm), eroded shells and heavier soft tissue masses. Therefore, SL-based regulations cannot serve as a proxy for maturity and harvest. The use of inappropriate minimum size limits (SL = 178 mm, 85 g market clean meat mass) has allowed significant juvenile harvest and the fishery appears to have truncated the SL size distribution of conchs with a flared shell lip (i.e. adults) over the last 15 years. The reduced SL observed in lipped conchs may lead to a significant impact on the reproductive success of the population as well as diminished economic yield from the fishery, as smaller adult conchs of the same age have lower gonad and meat weight. We believe this to be the first documentation of a decline in the SL of adult queen conchs, and that the SL-based size limits have contributed to this decline. Refinement of the individual size-based regulations for conch in Belize to LT will probably facilitate local recovery as well as regional harmonization of regulations. Future research in Belize should include movement dynamics of conch in relation to replenishment zone size and spillover as well as the importance of deep-water conch to shallow-water recruitment, which is thought to be limited.
KW - Belize
KW - coral reef
KW - management measures
KW - overfishing
KW - queen conch
KW - seagrass
KW - small-scale fisheries
UR - http://www.scopus.com/inward/record.url?scp=85068157952&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85068157952&partnerID=8YFLogxK
U2 - 10.1002/aqc.3147
DO - 10.1002/aqc.3147
M3 - Article
AN - SCOPUS:85068157952
JO - Aquatic Conservation: Marine and Freshwater Ecosystems
JF - Aquatic Conservation: Marine and Freshwater Ecosystems
SN - 1052-7613
ER -