Zoo 511: Ecology of Fishes Lab
Barbara Heindl
Assignment 1: Ecology of your fish
February 13, 2008
Crecco, V.A., and T.F. Savoy. 1985. Effects of biotic and abiotic factors on growth and
relative survival of young American shad, Alosa sapidissima, in the Connecticut River.
Canadian Journal of Fisheries and Aquatic Sciences 42: 1640-1648.
1. What Factor did the paper identify as influencing your species?
Factors in this study included temporal oscillations in zooplankton abundance, river flows
and temperature in the Connecticut River and their influence on survival rates of larval
and juvenile American shad.
2. How did that factor influence your species according to the authors?
According to the authors, the factors above influenced very young (first feeders)
American shads greatly. These factors appear to affect older juveniles less. The authors
suggested that later juvenile growth was more affected by intraspecific competition. They
also mentioned that later growth might be less affected by these factors because changes
in these factors are less likely later in the season when juveniles are older.
3. Were there figures in the paper? If so, did those figures help you understand the point
of the paper? Why or why not?
This paper had a lot of figures. Most of them seemed to be data tables which didn’t help
me understand much about the study. To be honest I glanced over most of these because
they didn’t seem to have a lot of use for understanding the paper, just raw data. There
were also some graphs which were more useful. In the paper they mentioned that parts of
the study showed non significant linear and non- linear relationships, while these were
shown in tables I think the information would have been more useful and easier to
understand in a graph or other figure.
Limburg, K.E. 1996. Growth and migration of 0-year American shad (Alosa
sapidissima)in the Hudson river estruary: otolith microstructural analysis. Canadian
Journal of Fisheries and Aquatic Sciences 53: 220-238.
1. What Factor did the paper identify as influencing your species?
The influence of size, age and declining seasonal temperatures on migratory success of
American shad juveniles.
2. How did that factor influence your species according to the authors?
According to the author size and age both seem to affect migratory success. Older
cohorts of fish tend to move down river sooner and within age groups of fish the larger
individuals tended to move faster than smaller. All fish in the study experienced
diminished fat storage later suggesting an advantage to migrating earlier in the season.
Parasites were also more frequent in the intestines of fish that migrated later The author
also says that migratory success/ cues do not seem to be determined by seasonal
temperature change since movement of the species occurred before temperatures dropped
significantly in the fall.
3. Were there figures in the paper? If so, did those figures help you understand the point
of the paper? Why or why not?
There were many figures in this paper. Figures were explained appropriately in the text
and were helpful in understanding the paper. Especially since the author talked about
many different aspects influencing the study. The figures illustrated the authors main
points an provided good support for the study. The author also included figures like maps
of the area which help put the study into perspective.
Doran, M.M., Johnson, T.B. and Kitchell, J.F. 1998. Consequences of prey fish
community dynamics on lake trout ( Salvelinus namaycush) foraging efficiency in Lake
Superior. Canadian Journal of Fisheries and Aquatic Sciences 55: 1273-1284.
1. What Factor did the paper identify as influencing your species?
Diet change (herring to rainbow smelt) affects on lake trout.
2. How did that factor influence your species according to the authors?
The authors found that growth at age was lower for trout that primarily ate rainbow smelt.
However trout continue to eat more smelt then herring. Traditionally lake trout mainly
consumed herring. The authors think this might be happening because of earlier piscivory
shifts in individuals associated with smaller gape limitations due to size. Traditionally
piscivory shift was later and the fish remained on an insectivore diet till the gape was
large enough to eat herring however, when rainbow smelt became more abundant than
herring the species began switching to piscivory sooner because consumption of rainbow
smelt required a smaller gape size.
3. Were there figures in the paper? If so, did those figures help you understand the point
of the paper? Why or why not?
This paper had many figures including less convention figures to describe aspects of the
study. I found these figures useful for understanding the paper. I am not a very graph
oriented person and sometimes different less conventional figures help illustrate aspects
of the paper more then graphs. It also helps to think about the paper in a different way,
the more variety there is in figures the easier for me to put the different figures together
and get the larger purpose of the paper.
Fabrizio, M.C., Dorazio, R.M., and Schram, S.T. 2001. Dynamics of individual growth in
a recovering population of lake trout (Salvelinus namaycush) . Canadian Journal of
Fisheries and Aquatic Sciences 58: 262-272.
1. What Factor did the paper identify as influencing your species?
The Gull Island Shoal refuge and its influences on the growth rates of lake trout.
2. How did that factor influence your species according to the authors?
Growth after a period in the refuge was slower but still continued. The study showed that
growth was similar in hatchery and wild caught fish. The establishment of the rfuge
increased the number of lake trout but decreased the growth rate. The study however did
not determine if the growth rate decrease was a caused by an increase in lake trout
abundance.
3. Were there figures in the paper? If so, did those figures help you understand the point
of the paper? Why or why not?
This paper also had figures including graphs and maps of the area. The maps help me put
it in context and internalize that this is a case study in an actual population not just a lab
study. The graphs were successful in illustrating the difference between refuge and post
refuge growth rates as well as the difference between wild fish and those raised in a
hatchery. Being able to visually compare variables helps illustrate all the facets of this
study.