User:B21RM250/Capelin

Diet
Capelin are planktivorous fishes that forage in the pelagic zone. Studies analyzing diet in populations of Capelin in both the arctic marine environment as well as in west Greenland waters show that their diet consists upon primarily euphausiids, amphipods, and copepods. As capelin individuals grow, the composition of their diet changes. Smaller capelin primarily consume smaller prey (copepods) and shift their diet towards feeding on primarily larger euphausiids and amphipods as body and gape size increases. The sufficient distribution and abundance of these zooplankton is necessary for capelin to meet energy requirements for many stages of their life cycle that allow them to persist throughout their range. Capelin occupy a similar dietary niche polar cod, which leads to a potential for interspecific competition between the two species.

Reproduction

In ocean spawning capelin populations, it has been observed that both male and female capelin are semelparous and die after spawning. This difference observed between capelin populations shows that capelin are physiologically capable of an iteroparous or semelparous reproductive mode depending on spawning habitat.

Studies on two populations of Newfoundland capelin which spawn in two distinct habitats found a lack of evidence of genetic variability between beach and deep-water spawners. This provides support for the species being facultative spawners. Capelin may select optimal spawning location based on abiotic factors such as temperature range and sediment. The optimal temperature range for capelin eggs that leads to greatest hatching success and offspring quality appears when eggs are incubated between 5°C and 10 °C. This optimal temperature range provides support that individual capelin are able to select spawning location based on temperature, as temperature is the one of most variable factors between beach and deep-water spawning habitats for capelin. There is also evidence that shows that temperature is not the only factor at play when it comes to selection of spawning habitat. When both habitats are simultaneously experiencing temperatures in the optimal range, capelin are found to spawn in both habitats. This may be an advantageous strategy that leads to increased fitness. Capelin have been observed to spawn at beaches when deep-water or subtidal habitat is lower than 2 °C and spawn in deep-water habitats when beach habitats temperature is consistently above 12 °C.