There are many Sciaenid species found in coastal water of Taiwan, and most of them can generate sound in the spawning season. However due to overfishing, the populations of these high economic value fishes have been greatly decreased. To study and protect Sciaenid, whose habitat should be identified to set up seasonal protection zones. In this study, easy and low cost measure by using passive sonar is proposed to map the habitat in the field. Measurement and analysis of Sciaenid¡¦s sound were performed to investigate its acoustic characteristic, and frequency range was found to be 350 to 1,500 Hz. The statistical distribution of sound levels can be built up by enough field measurement, therefore source levels can be defined in this method. In the addition, the transmission loss of in site shallow water was studied to compute the real decaying factor (TL=n*logR) of the survey site. By using 3 sonobuoys, with known source level distribution and transmission loss, the distance of possible habitat can then be inverted. Through enough measurements, the map of coastal habitat of Sciaenid can be generated with efficiency and accuracy.

Spotted seatrout, Cynoscion nebulosus, spawning locations as well as associated environmental variables were determined for Tampa Bay, Florida during the 2004 spawning season using a mobile hydrophone survey. Hydrophones, a type of underwater microphone, can be used to detect and record spawning sounds of soniferous fishes. During their spawning season in Tampa Bay which generally occurs between March and September, mature male spotted seatrout generate sounds associated with courtship in the crepuscular and evening periods by vibrating sonic muscles against the swim bladder. Active spawning sites can be located using hydrophones to find these calling males. Using a random stratified sampling method, 760 stations within Tampa Bay (46 % of the sampling universe) were sampled over the 2004 spawning season. Only 8% of sampled stations had large aggregations of spotted seatrout. Spawning, determined by the sound produced by large aggregations, was detected throughout the bay except for Hillsborough Bay and was most common in the lower bay and eastern region of the middle bay. Presence of submerged aquatic vegetation (SAV), proximity to shoreline, as well as high dissolved oxygen values and shallow depth were positively correlated with spawning areas. Courtship calls of sand seatrout, Cynoscion arenarius, and silver perch, Bairdiella chrysoura were also detected during the survey as they share an overlapping spawning season with spotted seatrout. Aggregations of all three species rarely occurred simultaneously. Sand seatrout and silver perch used different habitats within Tampa Bay to spawn and spawned with a much greater frequency than spotted seatrout. Courtship calls of spotted seatrout were analyzed both by ear and by received sound level to determine if signal processing could be used to assess courtship sound recordings. However, there was no clear relationship between the two methods.