Science Branch, Stock Assessment Division Pacific Biological Station (original) (raw)
Related papers
Status Assessments - Some Consequences of Using Different Salmon Indices
2004
In this report we apply a consistent analytical approach to several data types frequently used to index Pacific salmon in Canada. We compare results using different data types by examining the influence of three recent regime shifts. Conclusions from our evaluation of effects from the 1977 and 1989 regime shifts depended on which of three salmon abundance indices (catch, escapement, and total returns) and two survival indices (marine survival and recruits per spawner) were used. For instance, abundance shifts did not necessarily correspond with changes in survival, and regional variations existed, at least for coho. Results from our analysis confirm that different interpretations of salmon "status" may result, depending on which index is used.
Salmon As Status Indicators for North Pacific Ecosystems
Bulletin No, 2007
A new system of salmon status categorization will provide useful indicators of ocean conditions and climate variability in the North Pacific Ocean. Under Canada's new Wild Salmon Policy, biological status will be assessed and categorized for a few hundred largely independent lineages of chinook, sockeye, coho, chum, and pink salmon. Changes to the status of these Conservation Units, information regarding their oceanic distribution, and biological characteristics of fish returning to fresh water to spawn will be linked to the status of marine ecosystems. Data from short-lived species like pink salmon will inform the management of longer-lived species, including fish other than salmon. Each Conservation Unit will be categorized into one of three status zones based on the abundance and distribution of spawners or proxies thereof. Intensive studies of salmon returning to selected streams will determine the relative importance of factors operating in fresh versus oceanic waters and the role of natural vs. anthropogenic factors (e.g. fishing) on Conservation Unit status. These types of information collectively should provide important clues to marine health and carrying capacity. Things should also work the other way-ecosystem data (including oceanographic) will aid in the management of salmon and other marine species.
Trends in marine survival of Atlantic salmon populations in eastern Canada
ICES Journal of Marine Science, 2021
Declines in wild Atlantic salmon (Salmo salar) abundance throughout the north Atlantic are primarily attributed to decreases in survival at sea. However, comparing trends in marine survival among populations is challenging as data on both migrating smolts and returning adults are sparse and models are difficult to parameterize due to their varied life histories. We fit a hierarchical Bayesian maturity schedule model to data from seven populations in eastern Canada to estimate numbers of out-migrating smolts, survival in the first and second year at sea, and the proportion returning after 1 year. Trends in survival at sea were not consistent among populations; we observe positive, negative, and no correlations in these, suggesting that large-scale patterns of changes in marine survival are not necessarily representative for individual populations. Variation in return abundances was mostly explained by marine survival in the first winter at sea in all but one population. However, vari...
Transactions of The American Fisheries Society, 2004
The relationships between the spawning stock and the subsequent recruitment of pink salmon Oncorhynchus gorbuscha and sockeye salmon O. nerka from the Fraser River improve significantly when the data are separated by climate and ocean regimes. Our analyses show changes in these relationships as regimes shift, indicating that the trend in marine survival of pink and sockeye salmon changes on a decadal scale. In general, the climate and ocean regime from 1977 to 1988 was productive for pink and sockeye salmon. However, the regime in the 1990s was characterized by reduced productivity for both species. The occurrence of a natural shift in the trend of pink and sockeye salmon production on a decadal scale should be incorporated into the management of Pacific salmon stocks to ensure that annual catches, escapements, and planned stock abundances are consistent with the productivity of a particular regime.
Pink and chum salmon are the principal salmon harvest components in Southeast Alaska (SEAK) commercial fisheries and were valued at greater than $75 million from 2008 to 2010 (ADFG 2011). The combined harvests of both species in SEAK generally increased from about 10 to 50 million fish from 1960 to 2000. However, production trends have also varied annually, and over the last decade there has been evidence for a downward trend in harvest for both species. Stock structure also differs dramatically between species. Of the salmon harvested from 1997 to 2010, 98% of pink salmon were unmarked, presumably wild stocks, whereas 74% of chum salmon were identified as hatchery stocks (McNair 1998, 1999, 2000, 2001, 2002; Farrington 2003, 2004; White 2005, 2006, 2007, 2008, 2009, 2010, 2011). Recent variations in SEAK salmon production could be linked to ocean or freshwater conditions, species interactions, management or enhancement practices, or a combination thereof.
Status of Salmon in a Changing Environment: A Perspective from Alaska
Technical Report, 2019
Salmon are an important natural, economic, and cultural resource for many people across the northern Pacific Rim, including all five North Pacific Anadromous Fish Commission (NPAFC) member nations. Monitoring and understanding the status of salmon stocks is critical to the management and conservation of this shared resource, especially within the context of a changing and increasingly variable environment that these stocks interact in (e.g., ocean warming and ocean acidification). It is unclear what the future holds for our salmon populations, but we need to think about, and prepare for, the inevitable changes.