From Shark Fin Markets to Shark Populations: An Integrated Market Preference - Cohort Analysis of the Blacktip Shark (Carcharhinus Limbatus)
By Quentin S.W. Fong and James L. Anderson
ABSTRACT
The increasing demand for shark fins in Asia and the shark's life history pattern of slow growth, late maturity, and few offspring, have generated concerns regarding the sustainability of shark resources. This study estimates the optimal harvest size and age that maximizes gross revenue of shark fins for a single cohort of blacktip shark (Carcharhinus limbatus) under two management objectives. The first approach models the management of harvesting shark fins to maximize economic return to society based on a conjoint choice - cohort model. The second approach models management of harvesting shark fins to maximize economic return to the industry based on a hedonic price - cohort model. Results from these models differ with respect to optimal harvest ages and sizes under all discount rate and natural mortality rate scenarios. For example, optimal harvest sizes and ages for all scenarios from the conjoint choice - cohort model are greater than the maturation sizes/ages fro both male and female sharks. On the contrary, the optimal harvest sizes and ages for the hedonic price - cohort model fall below the reproductive maturation size and age for the female blacktip under all scenarios. Only the four most conservative scenarios (0 to 0.05 discount rates under 0.025 quarterly natural mortality) have optimal harvests greater than or equal to reproductive maturation size and age for male blacktip under the hedonic price - cohort model. Implications for fishery management policy is discussed based on these results.
KEYWORDS: Shark fin, conjoint analysis, hedonic price analysis, shark fishery management
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