Reproduction of the Blacktip Shark in the Gulf of Mexico

Ivy E Baremore,Michelle S Passerotti

doi:10.1080/19425120.2012.758204

Ivy E Baremore, Michelle S Passerotti

Open Access

https://doi.org/10.1080/19425120.2012.758204

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Abstract

AbstractReproductive and age data were collected for Blacktip Sharks Carcharhinus limbatus in the Gulf of Mexico from fishery‐dependent and ‐independent sources from 2006 to 2011 for stock assessment. A total of 757 Blacktip Sharks were sampled for reproductive analysis (399 females, 358 males), of which 741 were aged. Additional length and age data from a previous age and growth study on Blacktip Sharks in the Gulf of Mexico (207 females, 161 males) were incorporated into the size‐ and age‐at‐maturity analyses. The results indicated that Blacktip Sharks in the Gulf of Mexico have a synchronous, seasonal reproductive cycle and that females exhibit a biennial ovarian cycle. Male and female mating and parturition peaked from March to May. Length at 50% maturity was estimated to be 105.8 and 119.2 cm FL for males and females, respectively, while age at 50% maturity was calculated as 4.8 and 6.3 years. Near‐term pups averaged 38 cm FL, and gestation was approximately 12 months. Litter size was 4.5 pups per female, and fecundity was found to increase with both maternal size and age. Maternal body size—but not age—had a positive influence on offspring fitness. This represents the first comprehensive reproductive study of Blacktip Sharks in the Gulf of Mexico.Received October 1, 2012; accepted December 5, 2012

Highlights

Reproductive and age data were collected for Blacktip Sharks Carcharhinus limbatus in the Gulf of Mexico from fishery-dependent and -independent sources from 2006 to 2011 for stock assessment
A total of 757 Blacktip Sharks were sampled for reproductive analysis (399 females, 358 males), of which 741 were aged
The results indicated that Blacktip Sharks in the Gulf of Mexico have a synchronous, seasonal reproductive cycle and that females exhibit a biennial ovarian cycle

Summary

Introduction

Reproductive and age data were collected for Blacktip Sharks Carcharhinus limbatus in the Gulf of Mexico from fishery-dependent and -independent sources from 2006 to 2011 for stock assessment. Previous studies in the Gulf of Mexico have mostly focused on age and growth and used back-calculation methods to estimate age at maturity (Branstetter 1987; Killam and Parsons 1989; Carlson et al 2006) These studies have estimated size at maturity ranges for Gulf of Mexico Blacktip Sharks of 103–110 and 117–132 cm FL for males and females, respectively. Sizes and ages were estimated by Carlson et al (2006) for Blacktip Sharks in the western North Atlantic Ocean: median maturity estimates were 117 cm FL (5.0 years) for males and 126 cm FL (6.7 years) for females. Mating and ovulation were estimated to occur in May and June, agreeing with previous observations of the reproduction of Blacktip Sharks in the same area (Springer 1940; Bigelow and Schroeder 1948; Clark and von Schmidt 1965)

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