Interpreting spotted dolphin age distributions

Barlow, Jay and Hohn, Aleta A. (1984) Interpreting spotted dolphin age distributions. La Jolla, CA, NOAA/National Marine Fisheries Service/Southwest Fisheries Science Center, (NOAA Technical Memorandum NMFS, SWFC-4)

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Previous work has determined the age distribution from a sample of spotted dolphins (Stenella attenuata) killed in the eastern Pacific tuna purse-seine fishery. In this paper we examine the usefulness of this age distribution for estimating natural mortality rates. The observed age distribution has a deficiency of individuals from 5-15 years and cannot represent a stable age distribution. Sampling bias and errors in age interpretation are examined as possible causes of the "dip" in the observed age structure. Natural mortality rates are estimated for the 15+ age classes based on the assumption that these are sampled representatively. The resulting annual survival rate <D.82) is too low to allow population growth, given what is known about dolphin reproductive rates. (PDF contains 30 pages.)

Item Type: Monograph or Serial Issue
Title: Interpreting spotted dolphin age distributions
Personal Creator/Author:
Barlow, Jay
Hohn, Aleta A.
Series Name: NOAA Technical Memorandum NMFS
Number: SWFC-4
Date: 1984
Publisher: NOAA/National Marine Fisheries Service/Southwest Fisheries Science Center
Place of Publication: La Jolla, CA
Issuing Agency: United States National Marine Fisheries Service
Uncontrolled Keywords: Spotted dolphins; Stenella attenuata; seining; by catch; tuna fisheries
Subjects: Ecology
Item ID: 2460
Depositing User: Patti M. Marraro
Date Deposited: 21 Jul 2009 14:41
Last Modified: 29 Sep 2011 19:05

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