Author: William Converse KendallPublisher: Forgotten Books
ISBN: 9781333383237
Category : Science
Languages : en
Pages : 22
Book Description
Excerpt from Effects of the Menhaden and Mackerel Fisheries Upon the Fish Supply Eggs that are stationary or agglutinated, if they are from a single parent and all subject to the same conditions, will hatch at approximately the Same time and produce fish of comparatively uniform size. Aggregations of oating eggs are likely to be derived from several parents, laid at somewhat different times, and consequently will produce young of somewhat more diverse Sizes. In both instances the rate of growth of individuals varies, causing a difference in size, but on the whole each school of young fish is composed of individuals of fairly uniform sizes. This uniformity appears to be to a great extent perma nently maintained; yet it not infrequently happens that schools of two or more sizes become mixed, especially when a school is first broken up by any means and the scattered fish subsequently join other schools. Whether the schooling habit of the early stage is retained and is the basis of the schools of larger sizes up to adults is impossible to say. That such is the case is indicated by the comparative uniformity in size of individuals of schools of larger fish. Sometimes, however, a school is so large that it could hardly be the original brood or aggregation only, but several, or perhaps many, broods. But such a raft is composed of individuals of comparatively uniform sizes, or of sizes suggesting that the fish are of about the same age. The occurrence of such extensive rafts or bodies of uniformly sized fish in the spring of the year suggests that possibly the younger fish have a somewhat different habitat from the older ones at that season of the year when they are beyond observation - that is, after they have left the coast and prior to their return. But, as mentioned in the case of young fish, accidentally mixed schools of older fish of the same species, as well as schools containing unre lated species, are not uncommon. Mixed schools of large and smaller fish, or schools containing adventitious species, are likely to occur when the schools have been broken up and driven about by predaceous animals or by purse seiners. Such broken-up schools or straggling individuals, or even small schools, are prone to fall into the procession when a larger body of fish happens along, even though it is of a widely different species, if it is not inimical. Another possible cause of mingling is when the fish are feeding upon the same kind of food and the food happens for any reason to be bunched. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."
