Effect of gge on the recruitment of oocytes in the climbing perch, Anabas testudineus (Bloch)

Effect of age on the recruitment of oocytes in Anabas testudineus has been studied. For age determination opercular bones, otoliths and scales were collected from 210 adult females weight ranging between 18.0 g and 135.0 g and length between 8.5 cm and 20.5 cm. The scatter points of opercular bone length, scale length, and otolith length against the fish length showed linear relationships. The high values of coefficient of correlation (r) indicated that all hard parts grew proportionately with the corresponding growth of the fish. The marginal open zone in all hard parts had minimum width during the months of June and July indicating that the age ring might have been formed in the season immediately preceding these months due to spawning. The age rings were annulus in nature since the fish was found to spawn once in a year. Recruitment of oocytes were not affected by the age of the fish. No statistical significant difference was observed between the number of oocytes contained in the ovary of fishes falling into two different groups of the same body length.Bangladesh J. Zool. 43(1): 27-36, 2015

Functional Anatomy of Feeding in the Bluegill Sunfish, Lepomis Macrochirus: in Vivo Measurement of Bone Strain

The suction feeding mechanism of the bluegill sunfish, Lepomis macro-chirus, was studied in unrestrained fishes by the simultaneous recording of cranial muscle electromyograms, opercular cavity pressures, and opercular bone strain patterns. The electromyographic profile was similar to that of other advanced teleosts and consisted of preparatory, expansive, and compressive phases. The pectoral girdle remained nearly stationary during the strike. Opercular cavity pressures showed peak negative values of 145 cm H2O followed by a positive afterpressure of up to 50 cm H2O as water flowed out of the opercular chamber. Characteristic ‘coughing’ patterns showed an initial positive phase, followed by a negative phase, and then a final positive pressure pulse. Bone strain on the operculum was measured with rosette and single element strain gauges. Peak principal compression during the strike was 1800 μ6 and the peak strain rate was −615×103με/s, more than ten times that previously recorded in vertebrate bone during normal activity. Opercular bone strain results from the rapid reduction of pressure in the opercular cavity which causes the operculum to deform medially and does not result from muscle activity. The observed strain pattern is consistent with a stress regime of bending and twisting moments applied to the operculum during feeding. Two prominent orthogonal bony struts on the medial opercular surface are hypothesized to resist these bending and twisting moments.

Croissance en longueur et en poids des perchaudes Perca flavescens de la Grande Anse de l'île Perrot au lac Saint-Louis

In this study, growth in length is based upon age determination on the opercular bones of 2170 specimens, collected throughout the year from June 1967 to October 1969. The opercular bone shows allometric growth and this is taken into account in back calculations. Grande Anse perch show comparatively rapid growth. Growth of males is slower than that of females. Seasonal growth extends from May to September. Faster growing fish reach sexual maturity earlier in life. Length–weight relationship exponent is 3.107. Due to the weight of the gonads, female perch show maximum condition index values in winter.

Muscle Co-Ordination of the Respiratory Pump of the Carp (Cyprinus Carpio L.)

1. An analysis has been made of the pattern of activity of the muscles of the head of the carp, in relation to respiratory movements and pressures generated in the buccal and opercular cavity, during normal respiration and during coughing. 2. From comparison with the results of analyses carried out on other species of fish it is suggested that the respiratory movements of free-swimming teleosts in general conform to the following principles: the lateral expansions and contractions of the buccal and opercular cavities are always synchronous, but the lowering of the floor of the mouth may be synchronous with, or may precede, the lateral expansion. 3. In the carp the levator operculi muscle, although it inserts on the opercular bone, does not participate in the opercular pump but is the abductor of the lower jaw.