Abundance Dynamics of Pink Salmon, Oncorhynchus gorbuscha, as a Structured Process Determined by Many Factors
Despite the fact that pink salmon is a fish species with a short-cycle life span, its stock abundance dynamics exhibit features typical of common pelagic fish species with an average life-cycle duration. Interchanging periods of high and low pink salmon abundance levels relate to positive and negati...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.432.3339 http://www.npafc.org/new/publications/Technical Report/TR8/Radchenko.pdf |
| Summary: | Despite the fact that pink salmon is a fish species with a short-cycle life span, its stock abundance dynamics exhibit features typical of common pelagic fish species with an average life-cycle duration. Interchanging periods of high and low pink salmon abundance levels relate to positive and negative stock abundance trends inherent for major regional groups, Asian and American parts of aggregate stocks, and for pink salmon species as a whole (Radchenko et al. 2007). This feature of pink salmon abundance dynamics is determined by structural organization of the species and its populations. Major regional groups of pink salmon are divided into temporally isolated even- and odd-year populations. The life cycle of pink salmon can be conditionally divided into two periods: freshwater (including spawning, embryonic, and downstream migration phases) and marine (including inshore, marine waters in marginal seas, and oceanic phases). The phases repeat in reverse order until fish return from the sea and reach their spawning grounds. Most stocks, in turn, are separated by paired seasonal races with distinct morphological characteristics and spawning areas within river basins. Fig. 1. Pattern of pink salmon migrations during the life-cycle phases of aggregate stocks of the Sea of Okhotsk. Selected life-cycle phases are indicated by Roman numerals. For the purposes of assessing factors affecting mortality, abundance, and biomass losses on the basis of the pink salmon life cycle, I used typical data from an aggregated stock of Sea of Okhotsk pink salmon as an example (Fig. 1). The average abundance dynamics are based on data for 22 pink salmon generations spawning in 1989 to 2010 (Table 1). Average numbers and biomass estimates were calculated based on survey data, fishery statistics, and published literature. Table 1. Abundance dynamics of an average pink salmon generation throughout the different life-cycle phases using the aggregate stocks of the Sea of Okhotsk. Data are shown for generations of fish spawning in the years ... |
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