Edwin S. Iversen

Comparison of the Parasites of Pond-Reared and Wild Pink Shrimp (Penaeus duorarum Burkenroad) in South Florida

Abstract Pink shrimp, Penaeus duorarum Burkenroad, from natural populations in Biscayne Bay and from cultured populations in ponds operated by the University of Miami at Turkey Point, Florida, were examined for parasites during the summer of 1969. Parasites, with percentage incidence in parentheses, found in pond-reared shrimp were: the gregarines Cephalolobus penaeus Kruse, 1959 (11%), and Nematopsis penaeus Kruse, 1959 (20%); the larval cestodes Prochristianella penaeus Kruse, 1959 (17%), and Polypocephalus sp. (0.7%). Additional parasites found in wild shrimp but absent in pond-reared samples were: the microsporidian Thelohania duorara Iversen and Van Meter, 1959 (8%); an unidentified cestode of the genus Prochristianella (14%): and a larval nematode, probably Contracaecum habena (Linton, 1900) (13%). The incidence of parasitism in pond-reared shrimp is compared to that previously recorded from wild P. duorarum collected from Tortugas and Biscayne Bay. Absence or reduced incidence of certain parasites ...

Aspects of the Biology of the Tortugas Pink Shrimp, Penaeus duorarum

Abstract On the Tortugas grounds, off southern Florida, the female pink shrimp (Penaeus duorarum) had an estimated winter growth of 5 counts per pound per month (number of shrimp per pound with heads off). The males grew 7 counts per pound per month. The shrimp were tagged with Petersen disc tags. A general tendency was noted for the adult shrimp to move in a northwesterly direction. Female shrimp attain larger size than males in the Tortugas grounds and growth of the carapace, which is more easily measured than total length, is related linearly to total length. Size-frequency distributions suggest that small shrimp move from shallow water at the end of the Florida peninsula to the Tortugas grounds. Some salinity and temperature data are given.

A New Microsporidan Parasite from the Pink Shrimp (Penaeus duorarum)

Abstract A new species of microsporidian (sporozoan) parasite in the musculature of the pink shrimp Penaeus duorarum from three locations in south Florida is described. The name Thelohania duorata n. sp. is suggested for this parasite which causes a milky white color in pink shrimp. The ovoid spores measured 5.4 by 3.6 microns and had a polar filament of uniform diameter and 38 microns in length.

Research in Marine Aquaculture at the Institute of Marine Sciences, University of Miami

Abstract Within very recent times there has been an increase in attention paid to the possibility of culturing commercially valuable marine animals. The Institute of Marine Sciences, University of Miami has embarked on a research program to show feasibility of culturing shrimp and pompano. The basic initial assumption of the program is that profit must be the underlying stimulus for research and development of a new industry hence the concentration of effort on animals of high market value. A second assumption is that such culture, to be truly successful, must be intensive in character and divorced from the changeable marine environment where man is unable to control the host of limiting factors. The life history of the pink shrimp, Penaeus duorarum, and biological data on pompano, Trachinotus carolinus are briefly outlined. The research facility which consists of 7 elevated growing ponds, 16 20 ton capacity hatchery tanks and a hatchery-laboratory building is described. A brief discussion of limiting fac...

Recreational Fisheries Management

This sport has a high economic value and is of considerable importance in the entire fisheries industry (commercial and recreational). Fisheries management plans require knowledge of total harvest from fish stocks, yet management plans were based only upon the commercial catch figures available from government agencies until comparatively recently. Commercial catch figures are incomplete without recreational fisheries catch records. Recreational catch records, by reason of the very nature of recreational fisheries, are diffuse, difficult, and expensive to collect; and, because of this, recreational catches for many years were omitted in fisheries management programs and underestimations of total catches resulted. Such catches may be as much as 13 times greater than the commercial catch. In some areas, catches of king mackerel may be 15 times greater. Both commercial and recreational catches must be available and used for fish management equations to be effective.

Population Size and Fluctuations

To determine the effect of fishing on a stock, some estimate of the size of the stock that is being exploited is necessary. The weight or numbers of fish removed therefrom (fishing mortality) can be obtained from landing statistics. The question then is what portion of the total stock is not being harvested by the fishery? That is, how many are uncaught, or have escaped the fishery, remain to breed, and sustain the stock. Also, the remaining fish that survive predation and disease will grow to a larger size and thereby increase the biomass available to fishermen in subsequent fishing seasons. The amount that can be taken without harm to the fishery will be discussed in Chapter 12 and is generally called “surplus stock.” It is the amount that can be removed without harming the level of reproductive potential. At an extremely low level of fishing, many fish are unavailable for use by humans and are considered “wasted”; alternately, at extremely high levels of exploitation, the reproductive potential of the population is greatly reduced and recruitment failures can occur. What is sought in management plans is a suitable level of exploitation that is somewhere between the two extremes.

Major Resource Organisms Plants and Invertebrates

This chapter summarizes biological and fishery information on example species, or groups of species, of macroalgae and shellfish of commercial and/or recreational value. Productivity of the oceans, including methods of estimating total resource production, is discussed in Chapter 10.

Recreational Fishermen, Resources, Gear, and Value

There is a clear difference between commercial and true recreational fishing. The commercial fisherman fishes to earn a livelihood in a for-profit operation, while the true angler, the recreational fisherman, is engaged in a hobby or sport with no profit motive, and, as a rule, none of his catch is sold. It is true that some commercial fishermen, especially boat owners and captains, choose their occupation over a land job because they seek an independent way of life. Many simply have a love for the sea. The main motivation, nevertheless, is to earn a livelihood.

Major Resource Organisms Vertebrates

The importance of U.S. commercial finfishes in this volume is based on total weight landed of at least 100 million pounds (50,000 tons) per year. Annual landing records reported by the National Marine Fisheries Service, using a 5-year average (1977–1981), include anchovy, Atlantic herring, Gulf menhaden, salmon (pink and red), and tuna (skipjack and vellowfin).

Recreational Fisheries Biology

The difficulties of determining the extent and value of recreational fishing, together with the concept of an “inexhaustible sea,” have discouraged biological research on recreational species. Because many species are of both recreational and commercial value, commercial fisheries” research results (stimulated by population declines) have been utilized for the needs of recreational fisheries. The effects of increased fishing pressure on limited stocks of freshwater sport fish recently has encouraged research on the status of marine sport fish stocks (Table 17.1). Unfortunately for research needs on recreational species, when it came to budgeting funds, the high value of commercial fisheries appropriated the majority of available funds.