One of the biggest threats to the charr is the presence of invasive rainbow smelt
, a species of small fish that competes with charr for food and are suspected of eating charr's young.
Mature fish feed heavily on other fish, with rainbow smelt
being their preferred food.
Current threats to Cisco populations include nutrient-induced eutrophication, competition with invasive species like Rainbow Smelt
(Osmerus mordax), warming summer water temperature and extended thermal stratification, and overharvesting (Latta, 1995; Hrabik, et al, 1998; Stockwell et al, 2009; Jacobson et al., 2012).
Saffron cod (95% FO) and rainbow smelt
, Osmerus mordax, (55% FO) were most prevalent, followed by sculpins (9% FO).
She was interested in understanding how invasive rainbow smelt
were affecting the ecology of lakes and mercury levels in predatory fish, such as lake trout, walleye and northern pike.
Among specific topics are the postglacial recolonization and the loss of anadromy in rainbow smelt
from coastal Newfoundland, planning the management of Pacific salmon in a changing climate, modeling larval migration routes and spawning areas of Anguillid eels of New Zealand and Australia, detecting marine nutrient and organic matter inputs into multiple trophic levels in streams of Atlantic Canada and France, the status of diodromous fish species in the restored East Hammar Marsh in southern Iraq, and socio-economic and bio-political linkages in the management of tropical shad.
About the time the fish are done spawning, rainbow smelt
, gizzard shad, alewives, and several species of shiners come to these same areas on their respective spawning runs.
Balcher (1983) found that young rainbow smelt
(Osmerus mordax) prefer copepods to cladocerans, locating cladocerans from a similar distance to copepods but avoiding attacks on the spiny cladoceran forms.
masquinongy) in three, largemouth bass (Micropterus salmoides) in two, redear sunfish (Lepomis microlophus) in two, lake trout (Salvelinus namaycush) in two, brown trout (Salmo trutta) in two, rainbow smelt
(Osmerus mordax) in one, flathead catfish (Pylodictis olivaris) in one, and other salmonids in one.
Several studies, across broad taxonomic orders have demonstrated similar deviations from proportionality in the OS-FS relationship (e.g., flatfish (Rhombosolea tapirina and Ammotretis rostratus) [Jenkins, 1987], rainbow smelt
(Osmerus mordax) [Sirois et al., 1998], and Atlantic cod (Gadus morhua) [Otterlei et al., 2002]), which were also associated with life-stage transitions.
To take another example, several species of cisco, which were already depressed by the mid twentieth century by overfishing, were then dealt the final blow by three exotic species--the parasitic sea lamprey, a predator, and the alewife and rainbow smelt