Massachusetts Saltwater Fishing
Using Rod and Reel to Monitor Trends in Tautog Populations
Tautog, a popular species to target along the coast in the spring and fall, supports a lively and valuable recreational fishery in Massachusetts. Their habit of living among the rocky structures that provide them with food and shelter, creates a number of challenges for researchers interested in studying the tautog population’s status and trends.
Since 1978, DMF has used our inshore trawl survey to get information on the relative abundance of these fish in our waters, a strategy which may not represent the true trends in the population. Since bottom trawls are limited to sampling areas with few features along the bottom, the known rocky grounds of tautog are often inaccessible to this type of gear. To address this issue, a pilot study was designed to test the value of using a rod and reel survey to monitor tautog populations. These data could be used in combination with the trawl survey, or eventually prove to be the best method for population monitoring.
This grant-funded pilot study kicked off in the fall of 2016 and focused on the rocky and structured (“complex”) habitats of Buzzards Bay and Vineyard Sound. The 96 pre-selected complex habitats were studied using rod and reel during spring and fall months. In each sampling month, 48 of the 96 locations were targeted by conducting two fishing trips per week. On each trip, either a DMF vessel or a local charter boat was used with three to five anglers aboard. Using side-scan sonar, structured bottom was identified within the sampling area and the boat was then anchored on that structure. Angling was conducted for 45 minutes at each station using standardized fishing gear and green crabs for bait. All fish caught were identified by species, counted, and measured for length, and largely released alive. Additional data on tautog sex and maturity were collected on a subsample of individuals through otolith (inner ear bone) removal while others were released live after a pelvic fin spine sample was collected for aging purposes.
In addition to collecting individual fish data, several other variables that could influence catch rates were recorded at each location, including environmental conditions (water temperature, fishing depth, wave height, salinity and tidal phase), angler information, and fishing time. Using these data, statistical models were then created to determine the influence each factor had on the catch rates for tautog.
Results from the models showed that the factors most important for standardizing catch rates were the time of year fishing was conducted, the fishing depth, vessel type, bottom water temperature, tidal phase, and angler skill level. Temperature was indicated as an important influence on tautog presence or absence at a given location. Specifically, zero catch was predicted when the water was below 50° F.
In addition to modeling the catch rates of this pilot rod and reel study, comparison with the traditional trawl survey method was needed. Analysis of the rod and reel study indicated that it had a greater chance of detecting population changes than the trawl survey (estimated to be 20-40% chance of detecting a 20% change to the population using rod and reel vs. a less than 10% chance of detecting a 50% change to the population with the trawl gear).
These results suggest that rod and reel shows promise as a useful tautog population monitoring tool, but it is not without challenges. Appropriate standardization is one of the primary challenges to using a rod and reel survey as an index of abundance. Trawl gears are effective survey tools because they can be easily repeated. Standardizing rod and reel gear can be more challenging because it’s difficult to accurately report effective fishing time (due to hang ups, rig replacement, retrieval speed, etc.) and involves different angler skill levels and strategy. Additionally, in areas with lots of fish (where each hook could potentially catch a fish) an upper limit on the number of fish that we can study is created. Known as “hook saturation”, this is another important consideration to take into account when reviewing the data.
Despite the limitations, the use of rod and reel has promise for fishery-independent monitoring of tautog in Massachusetts waters. The development of a survey to sample the preferred, complex habitat of tautog is needed given all of the uncertainties and limitations of the trawl survey. Multiple years of data are also needed to fully examine the benefits of a rod and reel survey and to further compare how abundance numbers generated by the rod and reel and trawl surveys differ. A better understanding of the factors that affect tautog populations will help ensure management actions are appropriate and supportive of both the species wellbeing and the continued enjoyment by the recreational angler community of Massachusetts.