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Lecture

Lecture 21 22.docx

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Department
Biology
Course
BIO120H1
Professor
All Professors
Semester
Summer

Description
Lecture 21 -In the areas surrounding the Grand Banks, the water tends to be very shallow, creating warm and productive waters -There are in addition temperature and air gradients that move along this, and this surfaces nutrients and so-on -This is referred to as upwelling, and is the reason why these areas tend to be quite productive -Modern fishing innovations tend to be the reason why fishing has taken off, and since then cod yields exploded -In particular the invention of factory freezers have increased yields quite dramatically -Canadian law has extended gradually from 3 miles to 200 miles over its coast over concern of collapsing fisheries -The causes of the fishery collapse is a storm of bad political and economic reasons, as well as overinvestment and overcapitalization on fishing equipments -There is in addition a biological cause of the fishery collapse -The maximum sustainable yield means that when N is half of K, this will be the optimal and fastest growth period -The maximum sustainable yield is dependent on K being a constant, rather than depending on the changing conditions of the environment -If K were to change, if the water and habitat has changed, the Y intercept would be reached at a much smaller number -Part of the problem is because K is a theoretical assumption, and would mean if it was inaccurate than overfishing will still occur -The estimates for these N, B and D parameters were based on catch per unit effort, where going out to sea and estimating from catches at every trip -It was assumed that CPUE as an index of abundance was a true estimate of such -The number of eggs a fish produces is a function of body size, and there is a loss of big animals due to fishing practices Lecture 22 -Biologists looking at large and small islands, believed that bigger islands have larger species amount than smaller islands -Species richness was correlated quite strongly with island size, but in addition the distance to the nearest source to new species -Modern metapopulation concept, wh
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