Flathead

Abstract: This study reviews published information on Mugil cephalus from around the world, with recent genetic studies indicating that the flathead mullet may indeed be a species complex. Disciplines that are covered range from the taxonomy, genetics and systematics, through a variety of biological and ecological attributes, to biomarker and fisheries studies. The eurytopic nature of M. cephalus is emphasized, with the migratory life history covering a succession of very different aquatic environments (e.g. rivers, estuaries, coastal lakes/lagoons, marine littoral, open ocean), each of which is occupied for varying lengths of time, depending on the population characteristics within a region and the life-history stage of the species. Interpretation of these movements over time has been greatly enhanced by the use of otolith micro-chemistry which has enabled scientists to map out the different habitats occupied by individual fish at the different life stages. The range of physico-chemical attributes within these environments necessitates a wide tolerance to differing conditions, especially with regard to salinity, turbidity, dissolved oxygen and temperature, all of which are discussed in this review. The importance of M. cephalus to the ecological functioning of coastal systems is emphasized, as well as the pivotal role that this species fulfills in fisheries in some parts of the world. The parasites range from internal trematode and cestode infestations, to external branchyuran and copepod parasites, which use M. cephalus as either an intermediate or final host. The value of the flathead mullet as a biomarker for the monitoring of the health of coastal habitats is discussed, as well as its potential as an indicator or sentinel species for certain ecosystems.

Abstract: Life history, ecology, and population trends ofmigratory bull trout (Sabelinus confluentus) were investigated in the Flathead Lake and River system of northwest Montana and southeast Brit ish Columbia. We conducted these studies to obtain information to manage the species in l ight of threats posed by timber harvest, hydropower development, and a proposed coal mine. We estimated that about half the adult bull trout in Flathead Lake enbarked on a spawning migration from May through July, swimming 88-250 km to reach tributaries of the North and Middle Forks of the Flathead River. Bull trout entered the tributaries when water temperatures dropped below l2oC, and spawned from late August through early October after water temperatures were below 9oC. They spawned in areas of tributaries with low gradient, loosely compacted gravel, groundwater influence, and cover. After spawning, females left the tributaries and returned to the lake sooner than males. Most spawners were six or seyen years old and they averaged 628 mm in length. Juveniles were found close to the substrate in streams with summer maximum temperatures less than l5oC. Juveniles migrated out of the tributaries to the river system from June through August, at age I (18%), lI(49yo),IlI(32%), and IV (l%). Population status was monitored through redd counts and estimates of juvenile abundance in natal tributaries. The population may be l imited by quantity and quality of rearing and spawnrng habitat, and spawning escapement. Specific requirements for spawning and rearing habitat, and general sensitivity of each life stage, make the bull trout an excellent indicator of environmental disturbance.

Abstract: Based on the analysis of 1100 feces or scats, the seasonal diet of grizzly bears (Ursus arctos) in the Flathead drainage between 1979 and 1991 was estimated. In the early spring, major foods includ...