Dr. Gary Nelson, Jennifer Stritzel Thomson, Paul Caruso, John Boardman

> Striped Bass Monitoring Reports

Massachusetts is currently home to the largest recreational striped bass fishery in the country. Our total catch of stripers in 2000 alone approached 7.1 million fish. High population abundance of striped bass, the diversity of the Commonwealth's nearshore habitat and many sources of food for stripers are major factors contributing to the success of this fishery. Without a doubt, striped bass are the backbone of our recreational industry and provide enjoyment to hundreds of thousands of recreational anglers each year. Accordingly, we give this important resource a high level of attention by conducting many special investigations and monitoring programs designed to support the regional planning process.

Temperature Preferences

Figure 1. Proposed sampling of Salem Sound for 2006

We are conducting a special study in 2006 to examine the temperature preferences of striped bass during their summer residence. The thermal preferences of striped bass has been described for landlocked populations, but it is unknown if such preferences exist for striped bass in the continuously changing marine environment. In addition, as part of on-going research to determine if striped bass can impact their prey populations, the temperature data will be used in a computer model that estimates how much prey are eaten by striped bass.

1. What temperatures are experienced by striped bass?


2. To what extent does the environment influence the temperatures?


3. Do striped bass exhibit any temperature preferences or detectable behavioral patterns (e.g., day/night differences)?

Figure 2. Temperature-recording logger tag

To determine if striped bass exhibit a preference, temperature in the environment and temperature experienced by individual striped bass will be measured and compared. If striped bass experience similar temperature ranges that are available in the environment, they probably have no preference, but if they experience a smaller range in temperature, it would suggest a preference. With knowledge of temperature preference, the data gained from this project will also allow better understanding of how striped bass might react to climate change.

Figure 3. Temperature tag, bridle and backing tag

Based on a pilot study conducted in summer of 2005, the focus of the study in 2006 will be in Salem Sound, Massachusetts (Figure 1). Monitoring buoys will be placed at 15 sites and will measure temperature every 2 hours at various depths in the water column. The results obtained will allow a 3D picture of temperature in the Sound to be developed. Striped bass tagged with a temperature-recording logging tag (Figure 2) will then be released. The tag will be attached to the striped bass using a double-wire (diameter 0.33 mm stainless steel) bridal through the dorsal musculature with a backing plate on the opposite side of the fish to anchor the tag in place (Figures 3 and 4), and will record temperature every 2 hours. The tags record temperature over a range of -40 to 185oF, it can store up to 2048 readings and it is about 1.1 inches long. The words "Cutoff/Reward" and the DMF phone number are printed on the temperature tag and backing plate.

Figure 4. A 30" bass with the implanted temperature-recording logger tag and backing tag

Anglers who catch a tagged fish should remove the tag by cutting the stainless wire with wire cutters, retain the hexagonal temperature tag, and release the fish if it is undersized. Call the number on the tag (978-282-0308), and ask for Dr. Gary Nelson (x114) or Jennifer Stritzel-Thomson (x130), and we will arrange to have it picked-up if local or will ask to have it sent to us via mail. Lack of state protocols prohibits us from offering cash rewards, but if the tag is returned, we will send each angler a nice striped bass t-shirt and a Storm Deep Thunder 15 crank bait (combined value $25). Even if a tagged fish is caught outside the research area, the data are still invaluable to the understanding of the thermal ecology of striped bass, so please return any tag regardless of place of capture. If you have any questions, please call Dr. Gary Nelson at 978-282-0308 x114 or email me at Gary.Nelson@state.ma.us.

Age and Growth Sampling

1 year Growth Mark

Atlantic coast states that harvest striped bass are required, as part of the interstate management process, to characterize their landings. Monitoring of age, size, and sex composition of both commercial and recreational catch and landings of striped bass is indispensable for identifying the need for constructive revisions to management strategies and for confirming estimates of population parameters. In Massachusetts, we conduct annual sampling of the commercial harvest at seafood dealerships. Information collected from more than 9,500 stripers beginning in 1982 include length, weight, sex and scales from each fish examined. We also conduct annual sampling of the recreational harvest at several striped bass tournaments. In 2001, we solicited volunteer recreational anglers to collect scales from harvested and released fish to boost our sampling coverage. We can observe annual "growth rings" on fish scales and use them to estimate age composition of the catches and rate of growth.

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Tagging Studies

Anchor tag being inserted into striped bass before being released

Tagging and long-term monitoring of tag recoveries improves understanding of distribution of and movement of Atlantic striped bass stocks and generates vital information about annual survival rates. A state-federal cooperative study, now the largest of its kind, has applied tags to more than 370,000 wild and hatchery striped bass since 1985. Massachusetts DMF began a striped bass tagging study in 1991 as part of this ongoing state-federal cooperative effort and has tagged and released over 5,000 fishes. We employ skilled charterboat captains to guide and collect fish from shoal feedings grounds around Cape Cod. Our study furnishes the largest proportion of legal-size fish to this overall effort. Striped bass tagged in Massachusetts' waters have been recaptured as far north as New Brunswick, Canada and as far south as Georgia, USA.

Striped Bass Diet and Bioenergetics

> Food Habits of Striped Bass in Coastal Waters of Massachusetts

> Nelson, G. A., B. C. Chase, and J. D. Stockwell. 2006. Population consumption of fish and invertebrate prey by striped bass (Morone saxatilis) from coastal waters of Northern Massachusetts, USA. J. Northw. Atl. Fish. Sci., 36: 111–126. (674 Kb)

MarineFisheries conducted a study during 1997-2000 to address the issues of forage needs of the recovered striped bass population and the potential impacts of striped bass consumption on economically important prey species. This DMF research project was designed to provide diet information of striped bass and to build a computer-based bioenergetic model that allows us to estimate consumption rates of striped bass for any particular food item, such as river herring, menhaden, and even the commercially- important lobster. We collected diet information from over 3,000 striped bass collected from the North Shore, Cape Cod Bay, and Nantucket Sound regions of Massachusetts. Some findings of the study are summarized below.

We found that, in general, striped bass consumed mostly fish (menhaden, herring, silversides, and sand lance) and invertebrates (crabs, sand shrimp, and sea fleas); however, the amounts eaten varied depending on the month of summer, fish length, and where the striped bass were captured. Large bass (>24 inches) generally ate more invertebrates (mainly lobsters and crabs) than small bass (<24 inches), but small bass ate more fish (mainly menhaden during August-September) than large bass. Striped bass captured from rocky shorelines or offshore waters generally ate more invertebrates than bass captured from estuaries or harbors.

Striped Bass gut contents displaying different sizes of prey

We also found that the striped bass ate different sizes of prey. Fish prey ranged in size from 0.9" to 19" total length, and crab prey ranged in size from 0.1" to 4" carapace width. Individuals of menhaden and sand lance were generally <5" and the three dominant crabs (rock, green, and lady crabs) were generally <3". American lobsters eaten by striped bass were <2" carapace length.

Using the bioenergetic model, we estimated that an "average" striped bass of six years (27 inches in length) must eat about 16 pounds of prey to gain 1 pound in weight during June-September in Massachusetts' waters. Most energy contributing to the growth of this age class comes from different fish prey during June-July, but mainly from menhaden during August-September. These results confirmed the importance of fishes like menhaden to the survival and health of the striped bass population. (see Graph of Consumption below)