Poikilothermic fish have no control over their body temperature and their core body temperature can fluctuate broadly. While some ectothermic stenotherms thermoregulate their body temperature by inhabiting constant temperature environments, internal temperature of poikilotherms can widely vary.
In contrast to stenotherms, eurythermic fish can function at a wide range of water temperatures. They are often, but not necessarily, ectotherms. Desert Pupfish (Cyprinodon macularius), for example, can function in ambient temperatures ranging from 4 to 45 degrees Celsius. This thermoregulatory strategy requires that organs, enzymes, and metabolic processes can operate at varying environmental temperatures.
In contrast to eurytherms, senothermic fish can only function in a narrow range of water temperatures. Brook Trout (Salvelinus fontinalis), for example, function optimally approximately between 13 and 18 degrees Celsius. This thermoregulatory strategy requires that organs, enzymes, and metabolic processes operate in a small temperature band and makes these fish particularly vulnerable to environmental changes. … [Read more…]
Unlike endotherms which can metabolically control their own body temperature, ectotherms rely upon environmental temperatures for thermoregulation. Most fish are ectotherms. Ectothermy can be metabolically more efficient than endothermy because organisms do not have to expend any energy to self-regulate their body temperatures. However, they are at the mercy of their environment more than endotherms because they … [Read more…]
Unlike ectotherms, which rely upon environmental temperatures, endotherms are able to metabolically control their body temperature. This thermoregulatory strategy is rare among fish but is present in tunas and some sharks, including the Great White Shark (Carcharodon carcharias) and Shortfin Mako Shark (Isurus oxyrinchus). Endothermic tunas and sharks use a network of capillaries in their swimming muscles, … [Read more…]
An oceanodromous fish, like an anadromous or catadromous fish, is a migratory fish. Unlike anadromous or catadromous fish, an oceanodromous fish spends its whole life in salt water. Many oceanodromous fishes are termed highly migratory species (HMS) because of their ocean basin-sized migration routes. Many HMS are high trophic level fish and they migrate in search of food in … [Read more…]
Diadromous fish migrate between fresh and salt water. This term, coined by George S. Myers in 1949, refers to both anadromous and catadromous fishes. Diadromous life history strategies have evolved in numerous fish taxa. The complex life cycles do require complex osmoregulatory adaptation but the advantages of the given environments for specific life stages of … [Read more…]
A potamodromous fish, like an anadromous or catadromous fish, is a migratory fish. Unlike anadromous or catadromous fish, a potamodromous fish spends its whole life in fresh water. Generally, these migrations are for spawning purposes and cover short distances: from an upstream tributary to a mainsteam river or between connected lake and river systems. Some species, for example the … [Read more…]
Inland waters are defined by the United Nations’ Food and Agriculture Organization as the “surface water existing inland including lakes, ponds, streams, rivers, natural or artificial watercourses and reservoirs, and coastal lagoons and artificial waterbodies.” Inland fisheries, by consequence, are the fishing activities associated with those waterbodies. Inland fisheries “may involve capture of wild fish or raising … [Read more…]
A catadromous fish hatches and spawns in salt water but spends most of its life in fresh water. Catadromous life cycles are much less common than anadromous life cycles. American and European Eels (Anguilla rostrate and A. anguilla, respectively) are among the more famous fish that utilize this unusual migration pattern. They have a highly … [Read more…]