imminent danger of snagging and loss of the fishing gear). From these considerations, it is ideal that the two methods, with divers and beam trawl, should be
practised combined.
The management of exploitation by fishing of this gasteropod has a dual
function: to regulate its sustainable economic exploitation and to make use of this
service as an instrument for environment control, while keeping the population
R. venosa at a level which cannot constitute a threat to the ecosystem. Recent stock
assessment of R. venosa made by NIMRD’s experts during 2012–2014 estimated
the stock at the Romanian coast of the Black Sea around 14,000 t (with a
corresponding TAC value of about 5700 t/year) (NIMRD 2015).
Before the legalization of beam trawl use, R. venosa was harvested manually by
divers, but the yield proved to be very low, for example in 2012 only 588 t were
harvested, approximately 10.3% of the TAC. In 2013, after obtaining the authorisation for the use of beam trawl for harvesting rapa whelk (Order no. 1696 of
11.07.2013, Order no. 400 of 2013, setting-up the fishing prohibition periods and
areas, as well aquatic resources protection zones in 2013), the catch increased
2.27 times compared to 2012 (from 588 t in 2012 to 1338 tonnes in 2013), the TAC
being carried out at a rate of 23.5%.
23.2 Experimental
Manual harvesting activities of rapa whelk with divers are usually performed with
boats with sizes up to 10 m, which are powered either by engine or with paddles
(Fig. 23.1a, b).
For fishing activities using the beam trawl for R. venosa harvesting vessels of the
fleet segments 12–18 m and 24–40 m are used, equipped with installations/equipment that make it easy to perform a combined fishing, both with passive and active
gears (Fig. 23.2).
The beam trawl is a towed filtering gear in terms of construction and consists of a
beam (metal pipe) supported at its ends by two metal skids and the net (collection
bag consisting of cap, base and side). The traverse and feet are the backbone frame
that attaches the net, which in turn is fixed to the front of the foot on a frame of
resistance (rope, cable or chain), which aims to engage and direct to the concentration zone of the bag the target species (R. venosa) (Fig. 23.3).
During operation, the bottom of the beam trawl (base feet) is tangent to the
bottom of the sea, which allows harvesting of rapana fixed on the sandy or sandymuddy substrate. In the case of use of such tools, other organisms which live on the
bottom of the sea (such as mussels, crustaceans and gobies) may also be collected
by accident, for objective reasons (poor operation of the tool due to strong currents,
tides, variations in speed of trawling etc.). Depending on the equipment of the
vessels, they may operate with one or two beam trawls (Fig. 23.4).
23 New Equipment and Technologies Used for Rapa Whelk Harvesting at the. . .
399
practised combined.
The management of exploitation by fishing of this gasteropod has a dual
function: to regulate its sustainable economic exploitation and to make use of this
service as an instrument for environment control, while keeping the population
R. venosa at a level which cannot constitute a threat to the ecosystem. Recent stock
assessment of R. venosa made by NIMRD’s experts during 2012–2014 estimated
the stock at the Romanian coast of the Black Sea around 14,000 t (with a
corresponding TAC value of about 5700 t/year) (NIMRD 2015).
Before the legalization of beam trawl use, R. venosa was harvested manually by
divers, but the yield proved to be very low, for example in 2012 only 588 t were
harvested, approximately 10.3% of the TAC. In 2013, after obtaining the authorisation for the use of beam trawl for harvesting rapa whelk (Order no. 1696 of
11.07.2013, Order no. 400 of 2013, setting-up the fishing prohibition periods and
areas, as well aquatic resources protection zones in 2013), the catch increased
2.27 times compared to 2012 (from 588 t in 2012 to 1338 tonnes in 2013), the TAC
being carried out at a rate of 23.5%.
23.2 Experimental
Manual harvesting activities of rapa whelk with divers are usually performed with
boats with sizes up to 10 m, which are powered either by engine or with paddles
(Fig. 23.1a, b).
For fishing activities using the beam trawl for R. venosa harvesting vessels of the
fleet segments 12–18 m and 24–40 m are used, equipped with installations/equipment that make it easy to perform a combined fishing, both with passive and active
gears (Fig. 23.2).
The beam trawl is a towed filtering gear in terms of construction and consists of a
beam (metal pipe) supported at its ends by two metal skids and the net (collection
bag consisting of cap, base and side). The traverse and feet are the backbone frame
that attaches the net, which in turn is fixed to the front of the foot on a frame of
resistance (rope, cable or chain), which aims to engage and direct to the concentration zone of the bag the target species (R. venosa) (Fig. 23.3).
During operation, the bottom of the beam trawl (base feet) is tangent to the
bottom of the sea, which allows harvesting of rapana fixed on the sandy or sandymuddy substrate. In the case of use of such tools, other organisms which live on the
bottom of the sea (such as mussels, crustaceans and gobies) may also be collected
by accident, for objective reasons (poor operation of the tool due to strong currents,
tides, variations in speed of trawling etc.). Depending on the equipment of the
vessels, they may operate with one or two beam trawls (Fig. 23.4).
23 New Equipment and Technologies Used for Rapa Whelk Harvesting at the. . .
399