"The Kokanee, landlocked cousins of the sea-going Sockeye Salmon, were introduced to Lake Tahoe in 1944 by biologists working on the lake's north shore. These predecessors of today's inhabitants quickly adapted to the alpine environment, joining brown trout, rainbow trout and Mackinaw among the most prominent game fish in Lake Tahoe. However, no other species in Lake Tahoe offers such a spectacular show during their mating season.
Each autumn, nature calls mature Kokanee to return to the streams from which they were hatched, select a mate, spawn and die. As that time approaches, adult males develop a humped back and a heavy, hooked jaw, equipping them for the inevitable battles over both mates and territory, and both sexes turn from their usual silver/blue color to a brilliant red. Then, en masse, the fish make one mad dash to their mating grounds, fighting their way up the shallow stream, displaying their colors to attract a mate, then battling to protect the small patch of gravel streambed where they make their "redds" or nests."
- USDA Forest Service
For fish like the salmon, life is relatively short and reproduction is tied to death. For others like the Orange Roughy or Giant Sea Bass, life and growth seems indeterminately long.
For other fish like the orange roughy and ..., life is indeterminately long. Deepwater fishes tend to be long-lived and reproduce at a later age. As fishing technologies improve and make it possible to hunt fish in deepter waters, slow-to-mature fish are at higher risk of depletion.
If land animals rarely grow indefinitely, why are many fishes able to do this? Because their weight is supported by water, there is less cost to becoming heavier and heavier, unlike for land animals. But the reasons are complex and not well understood yet. The oldest largest fish tend to grow larger than land animals at a slower rate.
