Fish Ecology

Only available on StudyMode
  • Download(s) : 194
  • Published : February 27, 2013
Open Document
Text Preview
THE UNIVERSITY OF HULL

Department of Biological Sciences Level Five Examination May/June 2011 Fish Ecology Monday 16th May 2011, 9.30 - 11.30 a.m. 2 hours

Answer THREE questions Use diagrams where appropriate Use a separate book for each answer Where shown the % indicates the mark distribution within a question Graph paper provided

Do not open or turn over this exam paper, or start to write anything until told to by the Invigilator. Starting to write before permitted to do so may be seen as an attempt to use Unfair Means. [58277] Page 1 of 4 [Continued]

Answer THREE questions Use diagrams where appropriate Use a separate book for each answer Where shown the % indicates the mark distribution within a question

Graph paper provided

1.

a)

Discuss the concept of key factor analysis in relation to the generalized life history of fish. (50%) Describe how you would determine total mortality (Z) in exploited fish stocks from catch data. (30%) How is information on mortality used in fisheries management? (20%)

b)

c)

2.

a)

Discuss the adaptive significance of migration in the life history strategies of fish. (50%)

b)

Discuss briefly the relevance of predator prey interactions in structuring aquatic ecosystems. (50%)

3.

a)

Describe the characteristics of fish scales that allow them to be used for age and growth studies. (20%) Briefly describe the principle and method of “back calculating” growth in fish. (30%)

b)

c)

Figure 1 compares the back-calculated growth curve for roach in the River Don (a river in Yorkshire recovering from years of pollution) with the standard growth curve for roach in England and Wales. Explain the differences between the growth curves and what is possibly happening within the roach population of the river. Figure 2 provides the length frequency histogram for the roach population of the river and should be drawn upon to aid your explanation. (50%)

[58277]

Page 2 of 4

[Continued]

300 250 200

Length (mm)

150 100
Back calculated length

50 0 1 2 3 4 5

Standard growth curve

6

7

8

9 10

Age (years)
Figure 1 Comparison of back-calculated growth curve in the River Don with the standard growth curve.

130 120 110 100 90 80 70 60 50 40 30 20 10 0
0 20 40 60 80 100 120 140

River Don - Roach n = 1147

Frequency

160

180

200

220

240

260

Length class (mm)

Figure 2 [58277]

Length frequency histogram of roach caught in the River Don, July 2006. Page 3 of 4 [Continued]

280

4.

i) ii)

Define fecundity.

(10%)

Describe the methods commonly used to determine fecundity of fish populations. (40%) Discuss the relationships between fecundity and growth parameters. (20%) Outline the factors affecting the reproductive potential of fish populations. (30%) The depletion method is an important tool for determining the density of fish. Discuss its advantages and limitations. (50%)

iii)

iv)

5.

a)

b)

In a recent electric fishing survey of the River Piddle, the following data were obtained for a depletion sampling exercise, over 100 m of river not isolated by stop nets. Determine the population sizes of the roach and dace populations and discuss the accuracy of the outputs. (50%) Catches of roach and dace from the River Piddle Roach 72 45 23 Dace 57 11 18

Catch 1 Catch 2 Catch 3

6.

Using named examples, describe how behaviour and life history affect fish distribution.

[58277]

Page 4 of 4

[End]

tracking img