Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland

Growth and reproduction characteristics were described for 94 porpoises incidentally caught in gillnets during the summers of 1990 and 1991. Most porpoises (56%) were below five years of age. The oldest female was nine; the oldest male was twelve. Growth rates were similar for males and females unti...

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Main Author: Richardson, Shelly Faye
Format: Thesis
Language:English
Published: Memorial University of Newfoundland 1992
Subjects:
Online Access:https://research.library.mun.ca/5887/
https://research.library.mun.ca/5887/1/Richardson_ShellyFaye.pdf
https://research.library.mun.ca/5887/3/Richardson_ShellyFaye.pdf
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spelling ftmemorialuniv:oai:research.library.mun.ca:5887 2023-10-01T03:57:33+02:00 Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland Richardson, Shelly Faye 1992 application/pdf https://research.library.mun.ca/5887/ https://research.library.mun.ca/5887/1/Richardson_ShellyFaye.pdf https://research.library.mun.ca/5887/3/Richardson_ShellyFaye.pdf en eng Memorial University of Newfoundland https://research.library.mun.ca/5887/1/Richardson_ShellyFaye.pdf https://research.library.mun.ca/5887/3/Richardson_ShellyFaye.pdf Richardson, Shelly Faye <https://research.library.mun.ca/view/creator_az/Richardson=3AShelly_Faye=3A=3A.html> (1992) Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland. Masters thesis, Memorial University of Newfoundland. thesis_license Thesis NonPeerReviewed 1992 ftmemorialuniv 2023-09-03T06:45:34Z Growth and reproduction characteristics were described for 94 porpoises incidentally caught in gillnets during the summers of 1990 and 1991. Most porpoises (56%) were below five years of age. The oldest female was nine; the oldest male was twelve. Growth rates were similar for males and females until one year of age, at which time females grew longer and weighed more than males of similar ages. Using the Gompertz growth model, asymptotic values for body length were 142.9 cm for males and 156.3 cm for females and asymptotic values for weight were 49.1 kg and 61.6 kg for males and females respectively. -- The majority of mature females were pregnant (76%); a high proportion were simultaneously pregnant and lactating (35%). Mean age at sexual maturity for females was 3.1 years at a mean length of 146.4 cm. Younger females appear to have multiple ovulations or an increased proportion of luteinized follicles. Parturition occurred before the sampling period (before late June) and ovulation and conception were estimated to occur from early to late July. -- Sexual activity in males as indicated by spermatogenic activity was high during July, supporting estimates for the timing of ovulation and conception. On average, sexual maturity in males was estimated to occur at 3.0 years of age and at a length of 135.1 cm. There was a dramatic increase in testes weight, testes volume, and seminiferous tubule diameter at the onset of age three. -- Female porpoises from Newfoundland matured earlier and were larger than females from other areas. Dentinal deposition patterns in the teeth of harbor porpoises from Newfoundland were very different from those of the Bay of Fundy and suggest a new method of stock discrimination. Thesis Newfoundland Phocoena phocoena Memorial University of Newfoundland: Research Repository
institution Open Polar
collection Memorial University of Newfoundland: Research Repository
op_collection_id ftmemorialuniv
language English
description Growth and reproduction characteristics were described for 94 porpoises incidentally caught in gillnets during the summers of 1990 and 1991. Most porpoises (56%) were below five years of age. The oldest female was nine; the oldest male was twelve. Growth rates were similar for males and females until one year of age, at which time females grew longer and weighed more than males of similar ages. Using the Gompertz growth model, asymptotic values for body length were 142.9 cm for males and 156.3 cm for females and asymptotic values for weight were 49.1 kg and 61.6 kg for males and females respectively. -- The majority of mature females were pregnant (76%); a high proportion were simultaneously pregnant and lactating (35%). Mean age at sexual maturity for females was 3.1 years at a mean length of 146.4 cm. Younger females appear to have multiple ovulations or an increased proportion of luteinized follicles. Parturition occurred before the sampling period (before late June) and ovulation and conception were estimated to occur from early to late July. -- Sexual activity in males as indicated by spermatogenic activity was high during July, supporting estimates for the timing of ovulation and conception. On average, sexual maturity in males was estimated to occur at 3.0 years of age and at a length of 135.1 cm. There was a dramatic increase in testes weight, testes volume, and seminiferous tubule diameter at the onset of age three. -- Female porpoises from Newfoundland matured earlier and were larger than females from other areas. Dentinal deposition patterns in the teeth of harbor porpoises from Newfoundland were very different from those of the Bay of Fundy and suggest a new method of stock discrimination.
format Thesis
author Richardson, Shelly Faye
spellingShingle Richardson, Shelly Faye
Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
author_facet Richardson, Shelly Faye
author_sort Richardson, Shelly Faye
title Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
title_short Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
title_full Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
title_fullStr Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
title_full_unstemmed Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland
title_sort growth and reproduction in the harbor porpoise, phocoena phocoena (l.), from eastern newfoundland
publisher Memorial University of Newfoundland
publishDate 1992
url https://research.library.mun.ca/5887/
https://research.library.mun.ca/5887/1/Richardson_ShellyFaye.pdf
https://research.library.mun.ca/5887/3/Richardson_ShellyFaye.pdf
genre Newfoundland
Phocoena phocoena
genre_facet Newfoundland
Phocoena phocoena
op_relation https://research.library.mun.ca/5887/1/Richardson_ShellyFaye.pdf
https://research.library.mun.ca/5887/3/Richardson_ShellyFaye.pdf
Richardson, Shelly Faye <https://research.library.mun.ca/view/creator_az/Richardson=3AShelly_Faye=3A=3A.html> (1992) Growth and reproduction in the harbor porpoise, Phocoena phocoena (L.), from eastern Newfoundland. Masters thesis, Memorial University of Newfoundland.
op_rights thesis_license
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