Jeffrey C. Howe

Substrate preference in age-0 red snapper, Lutjanus campechanus

We tested age-0 red snapper, Lutjanus campechanus, for sand or shell substrate preference in a circular tank (1.5 m diameter × 0.6 m deep). The test tank was divided into two equal areas of whole oyster shell or sand substrates. All trials were video taped for 20 to 25 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. Mean ± SE time on shell was 11.6 ± 0.5 sec (4 fish trial−1) and 13.8 ± 1.1 sec (1 fish trial−1). Mean ± SE time on sand was 9.7 ± 0.4 sec (4 fish trial−1) and 8.9 ± 0.5 sec (1 fish trial−1). Fish spent significantly more time on shell compared to sand substrate in four-fish trials (paired t-test, p < 0.10) and also in single-fish trials (paired t-test, p < 0.05). Shell substrate may offer increased food and shelter for age-0 red snapper compared to sand substrate. However, a preference for shell substrate in the natural habitat may occur only during the nursery period, because as fish grow (> 100 mm TL) in the late fall they probably outgrow the shell habitat.

Standard length: not quite so standard

A variety of morphological, behavioral, physiological, and biochemical characteristics are used to identify and classify fishes. In practice though, it is more common to use morphometric measurements (i.e., body length, body depth, head length, eye diameter, jaw length) and meristics (i.e., fin ray, scale, teeth, gill raker, and lateral line pore counts). These morphometric measurements are usually presented as a proportion of either standard or total length. Unfortunately, in early works, it was often vague as to how lengths were taken. In addition, a protocol of how to measure standard length has never been standardized; consequently, several different definitions and interpretations exist. If a standardized protocol was implemented this could make comparisons of new measurements with older ones more difficult if the specimens are damaged, in a fragile state of preservation, or no longer exist. Standard length as a measurement has been in use for over a century, only the name is modern. This study reviews the chronological development of the concept of standard length and provides suggestions as to how ichthyologists should proceed into the next century.

Habitat utilization by postlarval and juvenile penaeid shrimps in Mobile Bay, Alabama

Densities of juvenile and postlarval Farfantepenaeus aztecus, F. duorarum, and Litopenaeus setiferus were compared in vegetated fringing marsh and adjacent nonvegetated areas over a range of environmental conditions in Mobile Bay, Alabama. Densities of all three species were significantly greater in vegetated than nonvegetated areas, with 82% of all penaeids found in vegetated areas. Among vegetated sites, significantly lower densities were found in oligohaline areas, whereas mesohaline areas had the highest densities. Significant positive correlations were found between density and salinity for F. aztecus and F. duorarum but not for L. setiferus. Emergent vegetation is important habitat for F. aztecus and F. duorarum as reported from other locations, and our data support a similar conclusion for L. setiferus. Shoreline emergent marsh vegetation is particularly important in Mobile Bay as it represents the only extensive vegetated habitat readily available to F. aztecus, F. duorarum, and L. setiferus.

Fishes of the bahamas and adjacent tropical waters, second edition

biologists is that the paper absorbs water slowly, but when it is wiped off quickly, no damage occurs. Alcohol penetrates quickly, but when wiped off and held up to dry, it causes no discoloration or wrinkling. Intended for an audience of ichthyologists and fishery biologists, this book will also aid anyone interested in the aquatic sciences by providing the latest information for anyone who interprets or provides ichthyofaunal data. Besides the expected readers among the ichthyologists and fishery biologists, this book will be useful to aquatic community ecologists as well as environmental and conservation biologists. The price (£120) is fairly steep for students, perhaps even beyond their reach, but for any professionals doing aquatic field studies or just identifying Indian fishes, the relative value of the book makes the price justifiable. This is an important contribution to the aquatic sciences to southern Asia. I recommend it.

A technique for deploying multiprobe data loggers to measure shallow water parameters

Low oxygen events have been suggested as causative factors for the reduction of the eastern oyster, Crassostrea virginica in Bon Secour Bay, Alabama. Because younger C. virginica may be less resistant to low oxygen levels which more often occur near the substrate, the height above the substrate may play an important role in their survival. To investigate the effect of low oxygen on the growth and mortality of C. virginica, a series of multiprobe data loggers were deployed in conjunction with C. virginica beds at different heights above the substrate. A simple and inexpensive method for deploying multiprobe data loggers at a defined height above the substrate in shallow bodies of water is discussed.

A technique for immobilizing and photographing small, live fishes

Abstract A common method for photographing small, live fishes involves the use of a restraining tank or photo cell for confining the specimen. Although the specimen is confined, the photographer faces the challenging and often time-consuming task of getting a sharp photograph of an active fish. A simple and inexpensive method for immobilizing and photographing small, live fishes is discussed.