sea lice.

that is right sea lice.

Fish Lice /Gill Lice - What are they?
By Rudy Lukacovic

Fishermen catching striped bass (as well as other species) in Chesapeake Bay may sometimes observe external parasites on the skin or gills of the fish they land. There are numerous species of external and internal parasites that can infect striped bass and other fish. These organisms occur naturally and under most circumstances do no great harm. More than 45 species of parasites and other microorganisms have been identified from Chesapeake Bay striped bass.

The gill lice (Ergasalis) are the most abundant and prevalent parasite of inland and coastal marine populations of striped bass. They are a parasitic copepod. Copepods are small, sometimes microscopic, invertebrates that are members of the plankton community. Heavy infestations of Ergasalis have occasionally been reported from the vicinities of Baltimore, Philadelphia and Washington DC. Frequently anglers conclude that striped bass with these parasites on their gills are fish newly arrived from the ocean. In fact, the life span of Ergasalis actually decreases when salinity reaches marine concentrations of 32 parts per thousand (ppt). High salinity also exhibited some detrimental effect on Ergasalis egg survival. Ergasalis reproduction and infestation of striped bass takes place throughout the bay in salinities varying from 0.5 to 30 ppt. Females parasites remain attached to the gills of fish throughout the winter. Ergasalis egg sacs appear during January and newly attached larvae are found in April. Juvenile striped bass can become infected as early as their third month of life while still in their natal rivers. As the fish increases in size so does infection intensity. Highest counts of full sized female Ergasalis were seen in late April and early May and again in June and in October. In any school of striped bass, many copepods may be just on a few fish.

Different species of Ergasalis may be specific to each species of fish. Ergasalis has been reported infecting largemouth bass and bluegill sunfish in freshwater lakes in Alabama. It has also been reported from striped bass in a freshwater lake where a heavy infestation may have caused sufficient stress for a bacterial disease to become established.

Other external parasites are occasionally observed on striped bass. Two other common external parasites are Argulus, the fish louse, which is another copepod like Ergasalis, and Lironeca, an isopod.

Argulus, the fish louse, is small, round and flattened. It is found on the skin and scales of striped bass from August to October. Its prevalence peaks in August. The presence of Argulus on striped bass can be coincidental with the appearance of small lesions on the base of the tail. It was also found on the skin of freshwater fish in Alabama.

Lironeca is a rather large isopod and its body is flattened top to bottom. It is commonly seen on the gills of striped bass, as well as on Atlantic menhaden and bluefish. It is mostly seen in the summer months at higher salinities.

There are numerous other parasites that are found internally in striped bass from protozoans to worms. These organisms are a normal part of environment in which all fish live. Under most circumstances they are tolerated by the fish but occasionally heavy infestations can be detrimental, leading to weakened immune systems and possible subsequent infection from bacteria and viruses.

Any concerns regarding human consumption of normal appearing fish can be addressed by proper cooking. Any disease or parasite will be killed during the normal cooking process. This does not apply to shellfish caught from areas closed due to pollution, or to finfish which are under consumption advisories because of tissue contamination. Common sense should be applied, and any abnormal appearing fish should not be eaten.

A few years ago alot of the stripers we caught in the Delaware Bay had large red sores the size of quarters on them. At that time we were told most of the fish that had the sores were from the Chesapeak Bay area. Here's a report ...

Stripers, for some unknown reason have a high susceptibility for mycobacteriosis, which has infected resident fish in Chesapeake Bay beginning in the 1980s. Recent studies, including the recent USGS/NOAA workshop on mycobacteriosis have shown a broad and increasing rate of infection.
Fish with mycobacteriosis develop a bacterial infection that causes inflammation and ugly lesions or sores on their skin; it also causes tissue destruction and formation of scar tissue in one or more organs, especially the kidneys and spleen. The disease has been characterized as a ?wasting disease? because it results in a loss of body mass and causes fish to look emaciated.
It is not known how fish actually become infected. Do they get it from their food, from stress, or from the water? And can they pass it on to others that swim nearby or when in a crowd? Among the possible reasons for the increase in mycobacteriosis (up about 62% from 1998 to 2005) are overpopulation and/or poor water quality combined with insufficient food sources.
The relationship between the occurrence of the disease and mortality of striped bass has not been definitely determined but there is evidence that mycobacteriosis may be having an impact on the bass population - more study on this question is needed. Some fishery biologists show that because of mycobacteriosis, natural mortality estimates ? number of fish that die from natural causes ? have increased dramatically for small bass in recent years, to perhaps as much as triple previous estimates. This could mean that assumptions surrounding current striped bass population levels are flawed.
Most of the fish with the disease are year-round residents of Chesapeake Bay although there have been reports that some infected fish are showing up as far north as New England waters. Other species in the bay, particularly Atlantic menhaden, a prey species of stripers and bluefish, also show increasing evidence of mycobacteriosis infection. One study showed much smaller numbers of infected fish in Delaware Bay to the north. Stripers further from the Bay display signs of the infection less often, perhaps because the migrating fish spend only a few months in the Bay while spawning, or perhaps because the symptoms lessen or are eliminated as fish find better sources of food and cleaner and cooler open water.
The infection is age-dependent and is even found in young-of-the-year fish. Infection rates can be as high as 50% for 3 to 4 year old males and up to 80% for age 6-year fish. Skin lesions are observed more in the fall than in other seasons.
People handling infected fish may develop skin lesions that can be difficult to treat. These fish should not be handled by individuals with cuts or sores on their hands. The workshop participants did not concern themselves with the health implications of handling or eating infected fish. Perhaps this issue is perceived to be too politically charged, but more understanding of the possible health ramifications of delivering infected fish to the seafood consuming public would seem to be of critical importance.
What happens to the sick stripers swimming in Chesapeake Bay? This is an important question since estimates are that Chesapeake Bay and its tributaries, during breeding times, hold about 70 percent of the Atlantic coast breeding stock. Mycobacteriosis usually causes death in an aquaculture environment but the effect on mortality in the wild is not yet certain. While the current mycobacteriosis outbreak may not as bad as it sounds, it certainly is not good. The mycobacteriosis problem combined with the smaller reproduction numbers from recent years, the continuing environmental decline in spawning areas, and the over fishing of breeding age fish doesn?t make the future look very bright.
A fair question to ask is how making striped bass a game fish would alleviate any of these negative pressures. Certainly it will not solve the mycobacteriosis problem, nor will it clean up Chesapeake Bay. On the other hand, when migratory bird populations were threatened, removing the pressure of market gunning provided the remaining ducks and geese the greatest possible opportunity to create strong broods: the results are undisputed.
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good info. thanks