James Phillips

 

Parental ecology of the plainfin midshipman (Porichthys notatus)

ABSTRACT

Statement of Problem

Systems with alternative reproductive strategies have one sex, which employs two or more different strategies to procreate with the other sex. A number of fishes have male alternative reproductive strategies known as sneakers. The plainfin midshipman's (Porichthys notatus) breeding system has parental males (Type I males) and sneaker males (Type II males). Parental males make nests under rocks in the intertidal zone, and attract females by making "humming" noises. Type II males attempt to snake into the nest while the female is spawning to steal copulations from the Type I male, who then takes care of the eggs after the female and Type II male have left.This system presents us with an opportunity to examine which nest site attributes sneaker males may be focussing on. Other well-studied breeding systems with sneaker males are colonial, and we can not decipher individual male preferences. The plainfin midshipman sneaker males, however, select specific nests with specific males in them, which enables us to examine which Type I male attributes sneakers may be selecting. I predict sneaker male preferences will mimic female midshipman preferences that have been found in previous studies. Sneaker male preferences will mimic female midshipman preference, because sneaker males can maximize fertilizations by doing so. I also predict that midshipman will be able to return to the same nest site year after year, and that there is a high cost associated with being a nest guarder (Type I male).

Sources of Data

This research was conducted in Tomales Bay, California from May 2006 through August 2007. All research was conducted on the extreme low tides of each month, to give access to the research sites. The data came from natural habitats (rocks) and artificial habitats at shores in the town of Marshall, California, and at Hearts Desire Beach in Tomales Bay State Park, California. Midshipman were found by overturning rocks in the low tide zone on these shores and were captured by hand. The rocks under which midshipman breed occur in the low tide zone which is only accessible when the tide is out and is below roughly -0.2m mean water level. Sampling time increases the lower the tide recedes, however, abiotic factors can alter tidal height.

To test the nest site size preference of Type II sneaker males, artificial habitats were created and placed at Hearts Desire Beach in Tomales Bay State Park. Concrete slabs were put in place in March, 2007 and were checked during every low tide cycle between April, 2007 and August, 2007. All midshipman found in artificial and natural habitats were tagged using 10mm nickel monel tags. The specific nest number and size was recorded, along with the total and standard length of the fish, and the weight of the fish,

 

Citation

Philllips, James Earl (2007) Parental ecology of the plainfin midshipman (Porichthys notatus). Masters thesis, Department of Biological Sciences, California State University, Sacramento.

James joined the lab in January of 2006 and finished in December 2007.

 

CSUS BIO SCI