Functional response of fishers in the Isle of Man scallop fishery

Abstract

To implement effective fisheries management, it is important to understand the variables influencing the distribution and intensity of fishing effort. The functional response of consumers to the availability of prey determines their impact on prey populations. The relationship between predator and prey observed in nature also applies to fishers and the populations they target. The present study focuses on the behaviour of a scallop dredging fleet fishing for Pecten maximus around the Isle of Man during a single fishing season. The functional response was investigated by examining the relationships between catches and fishing effort, scallop abundance and other variables. Scallop abundance was depleted rapidly during the first month of fishing. The increased patchiness of scallops towards the end of the season probably reduced their catchability, but fishers were able to maintain catch rates at intermediate abundance levels. The functional response did not conform to a particular type, but there was latent fishing capacity in the fishing fleet even at the highest levels of abundance. Therefore, reducing the number of vessels would not necessarily reduce fishing mortality unless combined with a reduction in the fishing power of individual vessels.

Confidentiality over fishing effort data threatens science and management progress

“…; Murray et al . ; Vermard et al . ) which is important in a management context to predict the outcome of different management scenarios, for example, displacement of fishing effort after a fishing closure (Dinmore et al .…”

Los seres humanos como depredadores: una visión general de las estrategias de depredación seguidas por cazadores con distintas motivaciones

“…An opportunistic strategy would be congruent with suggestions that hunter satisfaction is caused by multidimensional motivational processes, where the likelihood of killing game only is one component (Heberlein and Kuentzel, 2002). However, several studies failed to distinguish between response types, which could suggest low statistical power of the empirical tests, or that the ecological conditions behind Hollings (1959a) original models were not met (Murray, Hinz and Kaiser, 2011), which further exemplifies the complexities of human hunting and fishing behaviour.…”

Methodological considerations when using local knowledge to infer spatial patterns of resource exploitation in an Irish Sea fishery

“…The Isle of Man, located in the northern Irish Sea, has a territorial sea that extends 12 nautical miles (nm) (22.2 km) from the land and encompasses an area of 3965 km 2 (Murray et al, 2011). There are four primary fishing ports (Fig.…”

“…Each point displayed latitude, longitude, vessel course, and speed of vessels at 2 hourly intervals. Whilst VMS data does not specifically indicate if a vessel is fishing or not, fishing activity can be inferred by selecting only data points with a speed between 1.2 and 3.4 knots, identified from vessel speed-frequency distributions (Murray et al, 2011). In addition, logbook records were linked to each VMS record, indicating if they were targeting king or queen scallops, and the area of seabed swept determined from the towing speed and gear width, as described in Murray et al (2013).…”