Marine Accessories

Fish can have a range of life cycles where all stages of development take place in a small confined area like a pond or a stream to life cycles that take place over thousands of kilometers from streams to oceans and back to streams. The life cycles of Salmoniform fishes encompass almost all of the life cycle types and reproductive strategies. Some fish develop from the egg into the juvenile phase into the adult phase. Some fish species, particularly those in the deep sea, have larval stages distinctly separate from the juvenile and adult stage. The larvae often look very different from the mature fish. Salmoniform fishes are usually either male or female, but some of the deep sea versions are hermaphroditic, a reproductive strategy common in the deep sea.

Because of the value of salmon and trout fisheries, the life cycles of these two fish are very well documented. The results of this research have been used to identify the origin of salmon captured in ocean water to resolve arguments between nations. This information helps to better manage this valuable commodity and makes them a fish that can be a fish for sport fishing with the help of a fishfinder.

The reproductive strategies of fishes are varied. Sharks reproduce through internal fertilization and many shark species give birth to live young. Sharks that lay eggs produce large, tough shelled egg sacs often referred to as “mermaid’s purses.” Both sharks that give birth to live young and those that lay eggs produce relatively small numbers of young making it more important to preserve those species that are becoming overfished. Some bony fishes also bear live young, but most reproduce sexually through the fertilization of eggs joined by sperm in the water column. Females lay an enormous number of eggs to ensure fertilization as many eggs are eaten prior to encountering sperm in the water.

Like sharks, marine mammals also reproduce slowly and give birth to a limited number of young. Female whales, for example, give birth to a single calf and the nurse for many months, in some species longer than a year. Female whales and their calves form a strong bond during the nursing period, which helps whale species ensure a high rate of survival as the mother protects her young until the calf has reached a level of development where it can survive on its own.

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