Pacific Salmon

Kype

Posted by on

This Sockeye Salmon (Oncorhynchus nerka) displays a spawning kype (photo credit: Ron Harris).

Not to be confused with the popular internet phone/video chat platform of a similar name, kypes are hook like structure that develops on the jaw of some male salmonids during the spawning season.  Though Skype for salmon is still far fetched, this secondary sex characteristic does, in fact, have a role in communicating sexual fitness.

Research suggests that kype size has been linked to spawning frequency, via mate choice (that is, female salmon find a hooked jaw desirable) and competition on spawning grounds (namely, battles between males where the winner gets to pass on his genes).  For repeat spawners with an iteroparous reproductive strategy, the elongated jaw is reabsorbed after the spawning season ends.

Escapement

Posted by on

This spawned out Chinook Salmon contributes to the escapement estimate for its particular run.

Escapement is a term used in salmon management to mean, quite simply, how many salmon are able to “escape” premature death and complete their full life cycle.  These escapees have run the gauntlet of natural mortality, recreational fishing, commercial fishing, and other life-threatening episodes for the opportunity to spawn in freshwater.  Escapement is estimated by a number of different methods including fish counts (e.g., at a weir or dam viewing window) and carcass surveys (i.e., counting the dead salmon on spawning grounds).  For salmon managers, the amount of escapement for each salmon run informs population estimates and appropriate fishing quotas and other management strategies for future fishing seasons.

Phenology

Posted by on

Phenological events triggers Sockeye Salmon migrations (photo credit: USFWS).

Phenology is the study of seasonal or periodic cycles in ecosystems.  It is, essentially, “nature’s calendar.” For fish, phenology is often linked to timing of important life events such as spawning, migrations, and hatching.  These events are triggered by non-biological factors like day length, temperature, and precipitation.  If the timing of the main “cue” shifts, the alteration can have significant implications for the fish populations that have evolved to optimize the timing of their life events with that factor.

Many fall–spawning Pacific Salmon populations (Oncorhynchus spp.), for example, are beginning their freshwater migrations earlier than in the past (e.g. Kovach et al. 2015).  This consistent trend across species and populations strongly suggests that a shared environmental driver (i.e., climate change) is responsible.  Unfortunately, these altered behaviors can be maladaptive – Cooke et al. (2004) found that increased pre-spawn mortality rates – sometimes in excess of 90% – for several stocks of Fraser River sockeye salmon (Oncorhynchus nerka).

 

References

Cooke, S.J., Hinch, S.G., Farrell, A.P., F., L.M., Jones, S.R.M., Macdonald, J.S., Patterson, D.A., Healey, M.C., Van Der Kraak, G., 2004. Abnormal Migration Timing and High en route Mortality of Sockeye Salmon in the Fraser River, British Columbia. Fisheries 29, 22–33. doi:10.1577/1548-8446(2004)29

Kovach, R.P., Ellison, S.C., Pyare, S., Tallmon, D.A., 2015. Temporal patterns in adult salmon migration timing across southeast Alaska. Glob. Chang. Biol. 21, 1821–1833. doi:10.1111/gcb.12829