Effect of Activated Milt Residence Time on Landlocked Fall Chinook Salmon Egg Survival

Jill M Voorhees,Eric Krebs,Michael E Barnes,Jessica Shannon,Nathan Huysman

doi:10.4236/ojapps.2020.104011

Abstract

During artificial spawning of salmonids, activated sperm is allowed to remain in contact with eggs for variable durations. This study examined multiple residence times (20, 40, 60, 90, or 120 seconds) for activated sperm on landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs during spawning. There was no significant difference in egg survival to the eyed-stage of development or to hatch among any of the treatments, with a mean (SE) percent survival to the eyed stage of 63.9 (5.8). These results indicate that only relatively short residence times of activated milt on eggs during landlocked fall Chinook salmon spawning are needed to ensure egg survival, resulting in potentially substantial reductions in production-level spawning times and associated labor costs.

Highlights

During artificial spawning of salmonids, eggs and milt are manually removed from the fish, mixed in a pan, and water is added to initiate fertilization [1]
The results indicate that egg survival was not affected by activated sperm residence times as short as 20 seconds
The typical motile phase for Lake Oahe Chinook salmon sperm is less than one minute [8], and sperm motility in other salmonid species can be even less than 20 seconds [9]

Summary

Introduction

During artificial spawning of salmonids, eggs and milt are manually removed from the fish, mixed in a pan, and water is added to initiate fertilization [1]. To maximize the possibility of fertilization, residence times of the milt with the eggs after the addition of water have historically ranged from 2 to 15 minutes [1] [10] [11]. Lake Oahe salmon sperm motility ranges from 29 to 76 seconds, which is considerably less than two minutes [8]. It is possible that by allowing the milt and water mixture to be in contact with the eggs for two minutes, the process of rinsing the milt from the eggs at that time is contributing to egg mortality. The objective of this experiment was to investigate the effect of activated milt duration time on landlocked fall Chinook salmon egg survival

Methods

Results

Discussion