WHOLE FISH (SIZE)
1. Whole fish (Size): 656,000
We measure the length of fish to determine growth rates and identify when small fish enter the population from recent spawnings. When paired with length data, fish weight can be used to better understand fish condition and to determine the size of the total population. We collect these data from more than 200 species of fish.
2. Muscles (Health): 1,900
Comparing the percent "dry" weight to “wet” weight in fish muscle is one way to measure energy content, an indicator of fish condition. Studying the energy content of fish gives us insight to the quality of food available for predators that eat them.
3. Gonads (Maturity): 29,500
Gonads provide information about how many fish in the population are spawning. We evaluate maturity at sea during the research cruises. For some species, the gonad samples are analyzed under a microscope at the lab to confirm the maturity determined at sea. This deeper look also helps us better estimate maturity for fish sampled at time of the year when they are not spawning.
4. Stomachs (Diet): 12,300
Stomach contents help us understand what, and how much, fish eat providing insight into predator-prey interactions.
5. Livers (Health): 1,200
Fish liver weight gives us an indication of the overall health of a fish. Some fish, like cod, store a large amount of energy in their liver. Liver weight gives us an indication of the overall health of a fish.
6. Otoliths (Age): 76,400
Growth rings in fish otoliths allow us to determine fish age and to examine the overall health of a fish population. “Otolith” comes from the Greek for ear (“oto”) and stone (“lith”), so scientists usually call them “ear stones.” These small, hard structures float in the ear canal just under the brain, and help a fish with balance and hearing.