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Auke Bay Laboratory (ABL)

Marine Salmon Interactions Program

Gamete Incompatibility in Salmonids

Scientists at the Auke Bay Laboratoryís (ABL) Little Port Walter Marine Station designed and implemented a study to describe gamete incompatibility in Pacific salmon. Gamete incompatibility refers to the differential survival during fertilization and initial embryo development of progeny from specific female-male mating combinations. Gamete incompatibility is important because it can define speciation and may be an indication of inbreeding depression. The study will provide valuable insight into the genetic process within and between stocks of steelhead and Chinook salmon and will address fundamental issues that can drive conservation biology management decisions.

In May and August 2005, experiments were initiated using steelhead and Chinook salmon gametes in separate studies. In each experiment, 75 single-pair matings of all possible crosses were made in a 5◊5 factorial design with three replicate cells representing each female-male combination. Three blocks were completed using 5 different males and females for each block representing a total 15 different males and females, and after replications, 225 parings for each species. Families were assigned to incubator cells in a stratified random manner and incubated in vertical incubators. Survival data to eyed-egg stage and to hatch was collected and analyzed using an ANOVA (analysis of variance) package in SAS (data analysis software).

Initial statistical analysis for percent survival to the eyed-egg stage and hatch indicated that both steelhead and Chinook salmon showed significant female-male interactions. These results indicate that certain female-male combinations either inhibit fertilization or depress survival of early embryos. Further statistical analyses and analysis of biological samples taken during the experiment will help determine factors that are responsible for this interaction.

By Andy Gray and John Joyce

Report to Purse Seine Task Force

Joe Orsi of ABLís Marine Salmon Interactions Program reported on ABLís Southeast Coastal Monitoring (SECM) project to the Southeast Alaska Purse Seine Task Force in Ketchikan, Alaska, on 30 November 2005. This was a joint meeting of managers, researchers, and users of the pink salmon resource in southeastern Alaska. The purpose of the meeting was to review the 2005 purse seine fishery in the region with respect to seasonal commercial harvest, adult escapements, and processing capacity, and to discuss expectations for the 2006 season. The Purse Seine Task Force invited Orsi to present data from epipelagic ichthyofauna trawl surveys conducted by SECM that provide reliable forecast of pink salmon adult returns based on juvenile salmon indices.

The overview of the SECM project included preliminary results on forecasting chum salmon and a discussion of the possible ecological consequences of localized warming in the Southeast Alaska region of the Gulf of Alaska ecosystem. In 2004-05, SECM research documented anomalous warm waters in the area that appeared to trigger an earlier seaward migration of juvenile salmon; additional research in the region in late August in 2005 showed a northward range expansion of southern species such as Pacific sardine and Humboldt squid. There were additional corroborative reports at the meeting from purse seine fishers who also experienced warmer water temperatures than normal and had large catches of Pacific sardine throughout southeastern Alaska in July and August.

Documenting unusual and anomalous oceanographic conditions from commercial fishers in the region raises the prospect of utilizing this untapped source of data in the newly developing Southeast Alaska Ocean Observation System (SEAOOS). Integrating relevant data from research findings and the commercial fishing industry can help develop a better understanding of how ecosystems fluctuate.

By Joe Orsi and Alex Wertheimer


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