This paper deals with the sizes of California sardines (Sardinops caerulea) caught in the different areas of the Monterey and San Pedro regions off the coast of California. The present report is a sequel to Fish Bulletin 43, "The sizes of California sardines caught by the different fishing gear and in the different localities of the Monterey and San Pedro regions," except that in the present report no further work dealing with the sizes of sardines caught by different fishing gear was found necessary. The data of five more seasons have been added, allowing more definite conclusions, particularly for the Monterey region, where the data for only two seasons were available for the previous work. Also, a new fishing area has been added to the Monterey region.

This report is concerned only with the fishery as carried on in connection with the canning and reduction of sardines and does not include the fishery for the fresh fish and bait industry. The former phase is the more important and the one for which we have continuous sampling data.

The results of this investigation are of importance to cannery and reduction plant operators and to us, in showing the sizes of fish that can be expected in the different areas during an average season. Also additional evidence is furnished that indicates a southward movement of sardines along the California coast during the winter months.

The findings for the Monterey region tend to have more bearing on the sampling of sardines than do the findings for the San Pedro region. During the fall months there are significant size differences between sardines in the southern and northern areas of the Monterey region, whereas in the San Pedro region consistent size differences between sardines in the different areas are not present. Therefore, during a season when the fishery might be carried on for the most part in the northern areas of the Monterey region, we will have larger size-groups represented than during a season in which the fishery might be carried on for the most part in the southern areas.

The 1929–1930 sardine season at Monterey, which started on August 1, 1929, and ended February 15, 1930, found an influx of purse seine boats to supply sardines for the canneries. The lampara boat replaced the purse seine boat in this fishery in 1905, and until the fall of 1929 it had a virtual monopoly on the delivery of sardines to the Monterey canneries. At the close of the first season of the purse seine "comeback," it was deemed advisable to present the Monterey catch statistics for the 1929–1930 sardine season so that a comparison could be made of the success of the two types of fishing boats.

A key to understanding animal behavior is knowledge of the sensory information animals extract from their environment. For visually motivated tasks, the information animals obtain through their eyes is often assumed to be essentially the same as that perceived by humans. However, known differences in structure and processing among the visual systems of different animals clearly indicate that the world seen by each is different. A well-characterized difference between human and other animal visual systems is the number of types and spectral sensitivities of their photoreceptors. We are developing a technique, functional substitution, that exploits knowledge of these differences to portray for human subjects, colors as they would appear through the photoreceptors of another animal. In a specific application, we ask human subjects to rank hues of male threespine stickleback (Gasterosteus aculeatus) throats viewed through stickleback photopigments. We compare these ranks to ranks of the same throat hues viewed through normal human photoreceptors. We find essentially no difference between the two sets of rankings. This suggests that any differences in human and stickleback rankings of such hues would result from differences in post-receptoral neural processing. Using a previously developed model of stickleback neural processing, we established another ranking of the hues which was again essentially the same as the rankings produced by the human subjects. A growing literature indicates that stickleback do rank such hues in the evaluation of males as potential mates or threats. Although our results do not demonstrate that humans and stickleback use the same mechanisms to assess color, our experiments significantly failed to show that stickleback and human rankings of throat hues should be different. Nevertheless, a comparison of all these rankings to ranks derived from subjective color scoring by human observers suggests that color scoring may utilize other cues and should thus be used cautiously.

Male threespine stickleback (Gasterosteus aculeatus) use nuptial colors to attract mates and intimidate rivals. We quantified stickleback color and environmental lighting using methods independent of human perception to evaluate the information transmitted by male signals in a habitat where these signals are displayed. We also developed models of chromatic processing based on four cone photopigments (peak absorptions at 360, 445, 530 and 605 nm) characterized microspectrophotometrically in G. aculeatus and three other stickleback species. We show that a simple opponent mechanism receiving equally-weighted inputs from cones with peak absorptions at 445 nm and 605 nm efficiently encodes variation in male throat colors. An orthogonal opponent mechanism -- the difference between outputs of 530 nm cones and mean of outputs of 445 and 605 nm cones -- produces a neural signal that could be used for species recognition and would be largely insensitive to variation in male throat color. We also show that threespine stickleback throats/photopigments are optimized for this coding scheme. These and other findings lead to testable hypotheses about the spectral processing mechanisms present in the threespine stickleback visual systems and the evolutionary interactions that have shaped this signal/receiver system.