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Investigating the cost of migration in a freshwater fish

Martinsson, Johan (2012) BIOM01 20121
Degree Projects in Biology
Abstract
Abstract

Migration is a widespread phenomenon in nature, observed in many different taxa. Migration is often caused by changes in food availability, physical conditions and predation risks. Moving is energetically costly, and hence migration is likely to be a trade-off between increased survival and an energetic cost for migrating, the cost could take shape in decreased fecundity and lower body condition. Here, I investigate the reproductive cost of migrant and resident roach (Rutilus rutilus) by comparing body condition and reproductive investments. There were no significant reproductive costs to migration for either mature males or females, however a larger proportion of the migrating fish were immature suggesting that migration might... (More)
Abstract

Migration is a widespread phenomenon in nature, observed in many different taxa. Migration is often caused by changes in food availability, physical conditions and predation risks. Moving is energetically costly, and hence migration is likely to be a trade-off between increased survival and an energetic cost for migrating, the cost could take shape in decreased fecundity and lower body condition. Here, I investigate the reproductive cost of migrant and resident roach (Rutilus rutilus) by comparing body condition and reproductive investments. There were no significant reproductive costs to migration for either mature males or females, however a larger proportion of the migrating fish were immature suggesting that migration might delay the maturation age for migrants. Migrants also had larger eggs at the end of the sampling period which could potentially have fitness consequences for offspring. Future research should aim to investigate if the patterns observed in this paper are consistent and also investigate life-histories of migrants and residents by catching tagged fish with a known migratory history.

Popular science summary:

The cost of migration in a freshwater fish

Migration is a widespread phenomenon in nature, observed in many different taxa. Migration is often a result of changing physical conditions or changes in food availability, and although the migration often benefits the organism there should also be an energetic cost to migration. In this study I investigate the cost of migration in a freshwater fish, the common roach (Rutilus rutilus).

The roach is a partially migratory fish, which means that only a fraction of the population participates in the migration. The migration occurs during the fall, when fish migrate from the lake into the streams, and during the spring when fish migrate back into the lake. The migration is thought to be driven by predator avoidance, primarily from pike (Esox Lucius). Earlier studies have shown that the timing of the migration can potentially have powerful effects on the water quality and lake ecosystem, and since water is an important supply for many people, as a resource and for recreation, it is crucial to study this migration. Here I focus on the potential costs of migration i.e. the costs of moving up the streams and staying in the streams and hypothesize that migratory roach will be in worse condition and have less and smaller gametes (eggs and sperms) than resident roach.

In the spring of 2012 I caught migratory roach from the streams and resident roach from Lake Krankesjön and then compared their condition and the mass of the gametes. I also measured the size of the female eggs and compared residents vs. migrants to see if there was a difference in the quality of the eggs.

Results and Conclusions

I found no clear evidence of a cost to migration in roach. There was no difference in condition, reproductive investment or egg size between migrant and resident fish. However, there were significantly more immature fish in the stream than in the lake suggesting that migration might delay maturation age for migrants.

I found that the migrant eggs grew larger than resident eggs with time. Earlier studies have shown that fry from large eggs have a higher survival rate than fry from small eggs. If it is beneficial to stay in the lake to get better spawning grounds then the migrants can compensate this loss by producing large eggs giving fry with high survival. And this might be the mechanism that maintains the migration partial. However, further research is needed.

Advisors: Ben Chapman, Kaj Hulthén
Master´s Degree Project 30 credits in Biology 2012
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Martinsson, Johan
supervisor
organization
course
BIOM01 20121
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3633162
date added to LUP
2013-04-12 12:08:44
date last changed
2013-04-12 12:08:44
@misc{3633162,
  abstract     = {Abstract

Migration is a widespread phenomenon in nature, observed in many different taxa. Migration is often caused by changes in food availability, physical conditions and predation risks. Moving is energetically costly, and hence migration is likely to be a trade-off between increased survival and an energetic cost for migrating, the cost could take shape in decreased fecundity and lower body condition. Here, I investigate the reproductive cost of migrant and resident roach (Rutilus rutilus) by comparing body condition and reproductive investments. There were no significant reproductive costs to migration for either mature males or females, however a larger proportion of the migrating fish were immature suggesting that migration might delay the maturation age for migrants. Migrants also had larger eggs at the end of the sampling period which could potentially have fitness consequences for offspring. Future research should aim to investigate if the patterns observed in this paper are consistent and also investigate life-histories of migrants and residents by catching tagged fish with a known migratory history.

Popular science summary:

The cost of migration in a freshwater fish 

Migration is a widespread phenomenon in nature, observed in many different taxa. Migration is often a result of changing physical conditions or changes in food availability, and although the migration often benefits the organism there should also be an energetic cost to migration. In this study I investigate the cost of migration in a freshwater fish, the common roach (Rutilus rutilus). 

The roach is a partially migratory fish, which means that only a fraction of the population participates in the migration. The migration occurs during the fall, when fish migrate from the lake into the streams, and during the spring when fish migrate back into the lake. The migration is thought to be driven by predator avoidance, primarily from pike (Esox Lucius). Earlier studies have shown that the timing of the migration can potentially have powerful effects on the water quality and lake ecosystem, and since water is an important supply for many people, as a resource and for recreation, it is crucial to study this migration. Here I focus on the potential costs of migration i.e. the costs of moving up the streams and staying in the streams and hypothesize that migratory roach will be in worse condition and have less and smaller gametes (eggs and sperms) than resident roach. 

In the spring of 2012 I caught migratory roach from the streams and resident roach from Lake Krankesjön and then compared their condition and the mass of the gametes. I also measured the size of the female eggs and compared residents vs. migrants to see if there was a difference in the quality of the eggs. 

Results and Conclusions 

I found no clear evidence of a cost to migration in roach. There was no difference in condition, reproductive investment or egg size between migrant and resident fish. However, there were significantly more immature fish in the stream than in the lake suggesting that migration might delay maturation age for migrants. 

I found that the migrant eggs grew larger than resident eggs with time. Earlier studies have shown that fry from large eggs have a higher survival rate than fry from small eggs. If it is beneficial to stay in the lake to get better spawning grounds then the migrants can compensate this loss by producing large eggs giving fry with high survival. And this might be the mechanism that maintains the migration partial. However, further research is needed. 

Advisors: Ben Chapman, Kaj Hulthén 
Master´s Degree Project 30 credits in Biology 2012 
Department of Biology, Lund University},
  author       = {Martinsson, Johan},
  language     = {eng},
  note         = {Student Paper},
  title        = {Investigating the cost of migration in a freshwater fish},
  year         = {2012},
}