Reproductive Biology of Pacific Ocean Perch in the Gulf of Alaska

Christina L Conrath,Brian Knoth

doi:10.1080/19425120.2012.751941

Abstract

AbstractDespite the ecological and economic importance of rockfish fisheries in Alaska waters, little information is available concerning the reproductive biology of the majority of federally managed rockfish species in the Gulf of Alaska. Pacific Ocean Perch Sebastes alutus are the most abundant and commercially important rockfish in this region. This study examines the reproductive biology of Pacific Ocean Perch within the Gulf of Alaska, utilizing histological techniques to microscopically examine ovarian tissue. Pacific Ocean Perch samples were obtained throughout the year during National Marine Fisheries Service and Alaska Department of Fish and Game scientific surveys, as well as scientific charters. Ovaries of Pacific Ocean Perch began to ripen during the month of August with yolk increasing until February. Embryos appeared within the ovaries during February and continued to grow and develop until parturition in May. Results from this study indicate the fork length at 50% maturity is 33.4 cm and the age at 50% maturity is 8.4 years. Both of these values are smaller than those currently utilized in the stock assessment of Gulf of Alaska Pacific Ocean Perch. Results from this study will improve the stock assessment of this species by providing more accurate estimates of reproductive parameters and reducing the uncertainty in estimates of length and age at maturity.Received July 30, 2012; accepted November 16, 2012

Highlights

Despite the ecological and economic importance of rockfish fisheries in Alaska waters, little information is available concerning the reproductive biology of the majority of federally managed rockfish species in the Gulf of Alaska
This study examines the reproductive biology of Pacific Ocean Perch within the Gulf of Alaska, utilizing histological techniques to microscopically examine ovarian tissue
Pacific Ocean Perch Sebastes alutus occur from Japan to Cape Navarin in the Bering Sea, along the Aleutian Islands, throughout the Gulf of Alaska, and along the North American West Coast as far south as southern California (Allen and Smith 1988)

Summary

Introduction

Despite the ecological and economic importance of rockfish fisheries in Alaska waters, little information is available concerning the reproductive biology of the majority of federally managed rockfish species in the Gulf of Alaska. Results from this study indicate the fork length at 50% maturity is 33.4 cm and the age at 50% maturity is 8.4 years Both of these values are smaller than those currently utilized in the stock assessment of Gulf of Alaska Pacific Ocean Perch. The stock assessment for Pacific Ocean Perch in the Gulf of Alaska utilizes a separable age-structured model as the primary assessment tool This model incorporates maturity estimates that directly influence the estimation of stock biomass, and a very small change in this parameter can have a significant impact on the determination of total allowable catch calculated as a percentage of the stock biomass (Hanselman et al 2009). The values for age and length at maturity of this species currently utilized in the stock assessment model are derived from a non-peer-reviewed study in which visual techniques were used to assess maturity status and oocyte development (Hanselman et al 2009). The objective of this study is to examine the seasonality of the reproductive cycle and update the estimates of age and length at maturity for Pacific Ocean Perch in the Gulf of Alaska by utilizing more accurate histological techniques

Objectives

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Results

Conclusion