The Fishes - Food for Thought

The Fishes Food For Thought

Food for Thought... A rainbow trout will grow steadily until it begins spawning. Once trout start to spawn, they don't grow very much, but they will start growing again after their spawning years are over. When scientists stock BC lakes (put small hatchery fish into lakes) they often transplant sterile fish. Why would they do this?	Because rainbow trout are such prized sport fish, stocking sterile fish means that they will achieve larger sizes, not stop feeding, and not become spawn-bound (a condition where the fish retains its eggs or sperm and re-absorbs them rather than laying them).
Food for Thought... Dolly Varden is the name of a character in Charles Dickens novel "Barnaby Rudge". It is also the name of a dress style popular in the 1800s. How do you think the Dolly Varden got its name?	Have the children do some research on this topic. One theory is that the Dolly Varden reminded anglers of the gaudy dresses of the late 1800s.
Food for Thought... At the present time anglers must catch and release Dolly Varden because their numbers are so low. Can you think of a reason why this fish does not recover quickly from over-fishing?	Because they only spawn every other year, it is difficult for their numbers to recover.
Food for Thought... If this is their habitat, what would you guess about the way they move (slow or fast) ... why?	Consider the cold temperatures and the oxygen supply. These fish are probably very slow movers compared to other lake species.
Food for Thought... Arctic Grayling are easily endangered. What is it about their spawning habits puts this species at risk?	Because they do not build nests or redds, but rather just let their eggs fall to the stream bottom to hatch, the eggs become easy food for other fish in the lake.
Food for Thought... Bull Trout populations are very vulnerable to habitat degradation and the introduction of other fish species. For this reason, they are the only fish species currently considered in the British Columbia Forest Practices Code. What kinds of things could foresters do to keep Bull Trout safe?	Foresters should be especially careful about logging near lakeshores and rivers to ensure that logging does not cause extra sediments to flow into water bodies.
Food for Thought... Whitefish are hard to catch - they don't often stay on the fisherman's hook. What feature of their anatomy makes this happen?	Whitefish have small heads and no teeth.
Food for Thought... What feature does a whitefish not have that makes it distinctive from the Grayling?	The large dorsal fin.
Food for Thought... Why do you think brown trout were introduced to Canada. Do you think they were introduced to other countries as well?	Because they grow rapidly and are eager to bite the hook in summer when most anglers are active. Brown trout have been introduced to water bodies in many countries.
Food for Thought... If brook trout spawn in the fall, when do you think is the best time to catch them on your fly (when will they be the hungriest)?	They will be feeding the most before they spawn to build up their fat reserves. The best time to catch them is in the fall.
Food for Thought... Kokanee populations have been declining for years in some areas. In Okanagan Lake, one variety of Kokanee spawns right on the beach. What hazards might be faced by a fish that spawns on the beach?	Predation by people or animals, higher concentrations of pollution at the shoreline.
Food for Thought... Northern Pikeminnow will eat just about anything, but when they get bigger, they are mostly "piscivorous." "Piscis" is a Latin word that means "fish". So what do large Northern Pikeminnow mostly eat?	Small fish.
Food for Thought... The government has tried to get rid of the Redside Shiners that were introduced to interior lakes. Why? If Redside Shiners eat more and grow and breed faster than other species of fish, what might happen to the lake?	Redside Shiners were introduced to provide food for other fish, but they actually eat the same food as the sport fish. When they are successful shiners can use up vital food for native fish species.
Food for Thought... The Umatilla Dace may be a cross-breed between the Leopard and Speckled Dace. However, it is been discovered living in areas where one of the parents species does not live. How might you explain this?	The crossbreed may be more successful than its parents. The parent species may have died out.
Food for Thought... The Sucker's mouth is designed for eating food from the bottoms of lakes, rivers and streams. What kind of food do you suppose is best found on the bottom?	Detrities, rotting plant and animal matter.

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