Misty Lake sticklebacks COSEWIC asessment and status report: chapter 6

Biology

There is little information on the specific biology of either the lake or stream form of the Misty Lake sticklebacks. Until further studies are completed, it is assumed that much of their biology is similar to other Gasterosteus populations (for reviews of general biology see Wooton 1976; Bell and Foster 1994).

Life cycle and reproduction

Typically, the male stickleback provides parental care protecting and fanning the nest and continuing to defend and care for the young fish until they are capable of moving into cover to feed (Scott and Crossman 1973). The eggs take about 7 – 10 days to hatch, depending on water temperature. In general, threespine sticklebacks begin breeding in April and finish in September (Scott and Crossman 1973). McPhail (1994) described breeding timing for the Misty Lake stickleback pair; in both forms breeding began in April and ceased in July (gravid females were abundant during May and June).

Moodie (1972) described the life history of the lake form found in the Mayer Lake drainage. The lake form in Mayer Lake reproduces in its third summer. Males probably complete about five nesting cycles during a single breeding season before dying; the number of clutches produced by the females is unknown, but it is probably less. Reimchen (1992) found that the lake form in Drizzle Lake is unusual as it lives well beyond the first breeding season. These fish can live up to eight years, about twice the age of other studied populations of threespine stickleback.

Baker (pers. comm. 2006) was able to provide some preliminary information on the life history of the Misty Lake pair, based on size frequency data from fish sampled in 2005. Inlet fish breed at an earlier age than either the lake or outlet fish. Lake form females breed at ages 1 to 5, with ages 2 to 4 being fairly common (only one age 5 fish was present in the sample). The outlet fish appeared to be similar to the lake fish. Inlet females displayed a different life history primarily breeding at ages 1 and 2; very few were older than 3 years of age (about 90% of the females examined were two years old or younger). Inlet sticklebacks produce a higher number of eggs per spawning than either lake or outlet fish; egg size does not differ among the three habitats, but the eggs are quite large relative to those from other stickleback populations.

Herbivory/predation

Threespine sticklebacks are highly predated upon both by fish (including cannibalistic nest predation by other sticklebacks) and piscivorous birds (Scott and Crossman 1973).

Physiology

There is no published information on the physiology of the sticklebacks in the Misty Lake watershed.

Dispersal/migration

Hendry et al. (2002) found that lake sticklebacks placed in a stream environment will move downstream but not upstream. Stream fish were more likely to remain at the release site, but when they did move they travelled in both directions (either upstream or downstream). This was supported by the work of Moore and Hendry (2005) on gene flow between the populations.

Interspecific interactions

The lake form coexists with coastal cutthroat (Oncorhynchus clarkii), rainbow trout (O. mykiss), coho salmon (O. kisutch), Dolly Varden (Salvelinus malma) and prickly sculpin (Cottus asper). The inlet stream form is known to coexist with coastal cutthroat, coho salmon and Dolly Varden.

Diet has not been studied, but based on differences in the morphology of the mouth and gillrakers, the lake form is adapted to feed on zooplankton in the open water of the lake and the inlet stream form to forage on benthic macroinvertebrates (Lavin and McPhail 1986; McPhail 1994). 

Adaptability

Although various forms of Gasterosteus appear to have evolved rapidly following the last glacial epoch, it is clear that these threespine stickleback forms rely on stability of the environment (more specifically, maintenance of the selective regime) to maintain adaptive differences.  Thus, they are vulnerable to sudden changes in their environment, including species introductions and habitat change. This vulnerability has been demonstrated by the recent and rapid extinction of the Hadley Lake benthic-limnetic stickleback pair due to the introduction of brown catfish, Ameiurus nebulosus, (Hatfield 2001) and the collapse of the Enos Lake benthic-limnetic stickleback pair possibly as a result of habitat changes brought about by the introduction of signal crayfish, Pacifastacus leniusculus (COSEWIC 2002).

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