When you fish with a biologist like Dr. Hal Schramm, terms like “heritable” and “fecundity” tend to creep into the conversation. And that’s okay because he usually follows it up with an explanation using language I understand.
Fecundity is a fancy term used to describe fertility…the quality or power to produce abundantly. No further explanation needed…
Heritable is a bit tougher to explain, unless you listened in science class years back. Certain traits like eye color, height, hair, etc., are genetically pre-determined, and therefore are considered heritable. Old news? Yes, but the fact that fisheries scientists like Schramm are finding a fish’s catchability might be genetically predisposed is new!
The idea there may be distinct populations of fish, some easy to catch, others hard, is amazing.
In his Research Update column for the February 2011 edition of North American Fisherman magazine, Dr. Schramm highlights a Missouri study that found catch rates of largemouth bass in pond declined with continued fishing. The same thing was found on remote rivers in New Zealand. Even limiting anglers to one day of fishing every two weeks “caused a significant decrease in the catch rates of brown trout and a significant increase in the wariness of brown trout to the presence of anglers,” write Schramm.
The fact that fishing pressure shuts down a bite is not news to most anglers. You’ve seen it as have I, even in remote waters when the target is pike. But that’s when Dr. Schramm dropped the bomb. He highlighted the results of a long-term study (almost two decades in length) conducted by the Illinois Natural History Survey that showed catchability of a fish is an inherited trait!
Adult bass in a small impoundment were fished for a summer. Each time a fish was caught it would be marked so it could be identified later. When the lake was drained, those bass that were marked (caught) multiple times were then stocked in a separate pond to spawn. The bass that were not caught at all (or caught infrequently) were stocked in a different pond, also to spawn.
This process was repeated for three generations, after which the scientists found that the catch rate of “high vulnerability” fish remained consistently high while the catch rate of the “low vulnerability” fish declined with each generation!
Does this apply to species other than largemouth bass? Science will need to confirm this, but an educated guess would be yes. A bigger question is this: has catch-&-release come back to bite us?
The answer is a resounding NO! Catch & release actually helps keep more catchable fish in a population and the helps keep catch rates high than they otherwise would be.
-- Steve Pennaz, NAFC Executive Director