Proposed Method for
Stomach Content Analysis for Lake Herring, Bloater and Kiyi
In order to determine and compare the diets of herring, bloater
and kiyi we will identify, count, and weigh the items in their stomachs. Below is the method that I propose to use for
fish will be weighed, measured and frozen.
fish will be thawed, and the stomachs removed and preserved in 70%
contents will be placed into a watch glass for sorting under a dissecting
first 100 items will then be identified; macroinvertebrates will be
identified to the genus level when possible. Items will be sorted into separate
categories (Cx) and the number of items in each category will
be recorded (Cc).
category and the unidentified items will be placed in separate tared weigh
pans and dried at 90°c for 2 hours and weighed.
dry mass of each category (MCx) will be divided by the number
of items (NCx) to calculate the mean dry mass for an item (M/NCx).
- The MCx
of each category will be summed to get the mass of all the sorted items (Ms).
MCx when divided by Ms
will equal the percentage that each category contributes to the dry
mass (PCx). MCx/
Ms = PCx
will be added to the dry mass of the unsorted items (Mu) to
equal the dry mass of the stomach contents (Mt). PCx will be multiplied by Mt
to estimate the mass of each category in the stomach (TCx). TCx will be pooled for all
individuals within a species and used to compare diets between
This process will allow me to
efficiently analyze the stomach contents of fish by simplifying the counting,
sorting and identifying of stomach contents.
The data gained will be essential for understanding the ecology of
herring, bloater, and kiyi.