The abundance of the three species of endemic Black Sea marine mammals represented by
La abundancia de las tres especies endémicas de mamíferos marinos del Mar Negro, representada por
The marine mammals living in the Black Sea Romanian littoral waters, represented by the three species
The fishery-cetacean interaction is an issue that significantly affects the conservation of cetacean populations:
a) incidental mortality is caused by retention and entanglement in fishing gears;
b) food resources for cetaceans (dolphins are on top of the food chain) are depleted through overfishing, illegal fishing, disturbance of benthic biocoenosis and degradation of specific habitats of marine living resources;
c) cetacean behaviour, normal distribution, migration and reproduction are modified.
Fisheries and marine mammals have an impact on each other because they have similar vital interests, namely fish consumption, most often in the same areas and during the same time intervals.
Regular recording of incidental catches started in the entire Black Sea in 1968, but on the Romanian littoral recording began much later and the published data is very scarce after the moratorium for banning the commercial catching of the three cetacean species.
Up to 2001, no projects aimed at the monitoring of incidental catches and stranding of dolphins had been carried out, although research had been carried out on the fish catch, number of fishing gears, number of boats, fishing effort, seasons and fishing locations, fishing yield, and complementary and incidental catch. A research team belonging to the Marine Living Resources Department of the National Institute for Marine Research and Development "Grigore Antipa" (NIMRD), Constanta, who studied the status of fishery resources on the Romanian littoral, also made observations of incidental catches.
In 2001, the NIMRD launched the project "Conservation of the Dolphins from the Black Sea Romanian Waters" and gained financial support for it from the EU Life-Nature programmes. Two of the actions of this project focused on monitoring incidental catch in fishing gears and collecting data on stranding (
In order to collect the necessary information, NIMRD had an insufficient network; it was completed with new collaborators through specific partnership agreements with the Border Police, the Constanta Environmental Protection Inspectorate, the Department for Fishing and Aquaculture of the Ministry of Agriculture, private fishing enterprises and other organizations.
In its Conservation Plan, the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) stipulated as a conservation measure of cetaceans that all parties shall "collect and analyse data on direct and indirect interactions between humans and cetaceans in relation to inter alia fishing, industrial and touristic activities, and land-based and maritime pollution". Under the conviction that in some countries the basic implementation of the Agreement would be severely constrained by the lack of adequate financial resources, Article IX, paragraph 3 of the Agreement authorizes the Meeting of the Parties "to establish a supplementary conservation grant fund from voluntary contribution […] in order to increase the funds available for monitoring, research, training and projects relating to the conservation of cetaceans".
Resolution 2.4 of the Second Meeting of the Parties decided the conditions for awarding the grants from the Supplementary Fund. Fulfilling these conditions, the NIMRD prepared the Project and received the financial support for the Project "Assessment of the Extent of Current Cetacean By-catch and Strandings in the Romanian Black Sea Area". The project was carried out from April 2006 to March 2007, in collaboration with the "Mare Nostrum" NGO (
The Second Project with support from ACCOBAMS was carried out in 2010: "Development of a National Network for Monitoring the Black Sea Cetaceans (Stranded and By-caught) in Romania and Identifying Relevant Measures for the Mitigation of the Adverse Impact of Fisheries" (
In 2011, the data and information on accidental dolphin catches were provided by both notifications made by IJPF Constanta (Border Police County Inspectorate) and the records made by the NIMRD Constanta during the survey fishing carried-out with the bottom/mid-water trawl or turbot (
Year | |
|
|
Total |
---|---|---|---|---|
2002 | 29 | 29 | ||
2003 | 9 | 9 | ||
2004 | - | |||
2005 | - | |||
2006 | 20 | 2 | 22 | |
2007 | - | |||
2008 | - | |||
2009 | - | |||
2010 | 17 | 17 | ||
2011 | 54 | 54 |
A variety of fishing gears are used for active and passive fishing in the Romanian inshore and offshore coastal fishery.
The passive fishing gears generally include the tools for catching the fish migrating for spawning and feeding in shallow waters, namely (
- longlines and bottom lines;
- gillnets and trammel nets for Danube shad, turbot and sturgeons;
- sea pound nets.
Longlines are the main fishing gears used for spiny dogfish (
The bottom lines are traditional fishing gears exclusively used in fishing sturgeons in the Sf. Gheorghe - Ciotic sector. These fishing gears constitute a sort of barrier for sturgeons moving around the sector. Unlike longlines, bottom lines have no bait on the hooks: the fish are caught when trying to cross the hook barrage. Because of the way in which the bottom lines catch big fishes when they try to go beyond the hook curtain, it is very likely that dolphins can also fall prey to these fishing gears when they move around the sectors where they are fixed (
Danube shad trammel nets are made of three net sheets, a central one having a mesh size of 30 mm and a thread diameter of 0.3 mm and two outer ones having a mesh size of 250 mm and a thread diameter of 0.8 mm. These fishing gears are used to catch the Danube shad shoals off the Romanian coast between late March and mid-May, when this species migrates to the spawning grounds.
Unlike Danube shad trammel nets, turbot gillnets are made of one net sheet having a mesh size of 200 mm and a thread diameter of 0.5 mm (
The gillnets for sturgeons are made of one sheet, with a thread of 1.4 to 1.5 mm and a mesh size exceeding 100 mm as per the legislation in force, depending on the target species. Turbot and sturgeon gillnets and Danube shad trammel nets are considered fishing gears that cause victims among the dolphins. These fishing gears are made of thin, less visible and elastic threads that facilitate catching and tangling of the specimens crossing these nets.
Sea pound nets are fishing traps of large dimensions placed at depths of 7 to 12 m (
As the marine pound net is made of nets with a small mesh size, it does not facilitate dolphin tangling or catching. This fishing gear is also a large one, so in extreme situations dolphin specimens can enter these installations in search for food. In these cases, the dolphins can become captive, especially in pound nets installed on stakes, in which the aerial wall can be rather high above the water and thus constitute a real barrier for dolphins that enter the catching enclosure.
Another category of fishing gear used in the Romanian coastal zone includes active fishing gear: beach seine and mid-water trawl (
The trawl fishery in the Black Sea is seasonal owing to the limited period when target fish species are present in the area covered by the Romanian coastal trawlers. The trawl influences dolphin populations directly and indirectly. Because these gears have a large filtering surface (ca. 300 m2), it is possible for some dolphin specimens to enter the trawl, drown and die in the codend as they cannot get out to breathe (
The number of fishing gears decreased in Romania as follows: number of trawls from 3 to 2; trap nets from 21 to 15; beach seine from 18 to 3; gillnets from 10037 to 5202; hand lines from 1172 to 256 and longlines from 620 to 252 (
Each year, tens of dolphins die tragically when they are incidentally caught in the commercial fishing gears. Dolphins are not the target of fishing with these gears but, in search of food, they sometimes find the fishing nets where they get entangled or hooked, so they subsequently drown. The greatest hazard for Black Sea dolphins is turbot gillnets because of their number and area of distribution.
During the study period, incidental catches of dolphins were caused through the fraudulent fishing practiced by the Turkish boats in the Romanian exclusive economic zone (EEZ) and through the intensification of the fishing effort carried out with gillnets and trammel nets. In 2002, incidental catches of dolphins were registered during the fraudulent fishing performed by foreign trawlers in the Romanian EEZ in April 2002 (
We assessed that the total number of dolphins incidentally caught was about 100, but we could not bring all of them on board because many of the carcasses were in an advanced state of decomposition (the retrieval was carried out over seven days after the arrest of the illegal fishermen) and became detached from the nets during the retrieval.
The number of incidental catches resulting from fraudulent and authorized fishing of turbot using gillnets was 29 specimens belonging to
Following the estimation of the distribution of dolphin strandings on the Romanian littoral, we can summarize that they were recorded between Vama Veche and Portita, especially during the prohibition of turbot fishing (April-June), when this species (preferred food of
Years | |
|
|
Unidentified | Total |
---|---|---|---|---|---|
2002 | 20 | 2 | 13 | 21 | 56 |
2003 | 78 | 2 | 2 | 37 | 119 |
2004 | 7 | 2 | 4 | 5 | 18 |
2005 | 7 | 4 | 4 | 26 | 41 |
2006 | 33 | 2 | 2 | 67 | 104 |
2007 | 5 | 3 | 2 | - | 10 |
2008 | 16 | 1 | 2 | 4 | 23 |
2009 | 13 | - | 5 | - | 18 |
2010 | 35 | 1 | 6 | 42 | |
2011 | 45 | 3 | 4 | 52 |
Year | February | March | April | May | June | July | August | September | Total |
---|---|---|---|---|---|---|---|---|---|
2002 | - | 1 | 7 | 39 | 4 | 1 | 2 | 2 | 56 |
2003 | - | - | 5 | 18 | 3 | 83 | 10 | - | 119 |
2004 | - | 5 | 4 | 7 | - | 1 | 1 | 18 | |
2005 | - | - | 3 | 13 | 2 | 18 | 3 | 2 | 41 |
2006 | - | 6 | 9 | 30 | 20 | 35 | 1 | 3 | 104 |
2007 | 1 | - | 1 | 1 | 2 | 2 | 3 | - | 10 |
2008 | 1 | - | 4 | 5 | 9 | 2 | 2 | - | 23 |
2009 | - | - | 7 | 3 | 5 | 1 | 2 | - | 18 |
2010 | 6 | 4 | 7 | 20 | 2 | 3 | 42 | ||
2011 | 3 | 34 | 5 | 7 | 3 | 52 |
In 2003, 9 cetaceans pertaining to
In 2004 and 2005, no incidental catches were formally registered and the strandings were fewer than in previous years (
In 2006, cetacean incidental catches were identified in the industrial fishing with gillnets in four situations involving 22 specimens of the species
In 2007, 2008 and 2009, no incidental catch was officially recorded and strandings were fewer than in previous years (
In 2010, 17 specimens of
In the period analysed, the majority of accidental cetacean catches in gillnet gears involved the species
When abandoned gillnets lifted on board control vessels, by-caught dolphins are often found, usually decayed. These "ghost" tools are built in series with no markings, mechanically armed and especially designed for bottom stationary fishing. According to existing data (Report of the National Agency for Fisheries and Aquaculture), the total length of the "ghost" nets found since 2006 to date is about 90 km.
The situation of abandoned gears in 2011 is presented in
Period | Number of fishing gears |
---|---|
January | 14 monofilament gears abandoned at sea |
February | 25 monofilament gears abandoned at sea |
March | 5 monofilament gears abandoned at sea |
April | 106 monofilament gears abandoned at sea |
May | 39 monofilament gears and gillnets abandoned at sea |
June | 129 monofilament gears and gillnets abandoned at sea |
July | 24 monofilament gears abandoned at sea |
August | 10 monofilament gears abandoned at sea |
September | 6 monofilament gears abandoned at sea |
October | 8 monofilament gears abandoned at sea |
According to the information from economic agents practising specialized turbot fishing, on the Romanian coast the average number of dolphins accidentally caught by turbot gillnets with mesh size of 200 mm in regular checks (4-5 days, but conditional upon the weather) is 1-2 dolphins in 30-40 gillnets (
From an interview with a vessel skipper it was ascertained that in 150 gillnets with an average length of 60 m, the cetacean by-catch, especially of
Impact of fisheries on cetaceans
Fisheries can have a series of effects on cetaceans:
- modification (depletion or increase) of feeding possibilities;
- behavioural modification;
- alteration of the distribution, migration and breeding capacity.
Pelagic and coastal fishery can affect the cetacean populations through the overexploitation of the species that are feeding resources for them. Fishing activity can change the dolphins’ feeding behaviour and strategy. They are sometimes seen near trawlers and hauling trawls, and near or even in passive fishing gears (pound nets, gillnets and longlines).
Dolphin habitats are degrade by fishing gears in several ways:
- great numbers of fixed gears, pound nets, gillnets etc. can considerably reduce the vital space for dolphins and increase the possibility of being entangled;
- bottom trawling, in addition to its direct danger to dolphins, can destroy the benthic fauna, thus eliminating important links of the food chain;
- mid-water trawl hauling is also a direct threat, as there is the possibility of entanglement, but it also acts on the food resources; as it is very unselective, it can affect both adults and juveniles.
However, taking into account the number and area of coverage, turbot gillnets are the most dangerous fishing gears for Black Sea cetaceans.
The marine mammals living in the Romanian Black Sea littoral waters, represented by the three species
The fishery-cetacean interaction is an issue that significantly affects the conservation of cetacean populations, through incidental mortality produced by retention and entanglement in fishing gears; depletion of food resources for cetaceans through overfishing (dolphins are a the top of the food chain), illegal fishing, benthic biocoenosis disturbance and degradation of specific habitats of marine living resources; deterioration of cetacean habitats; and modification of cetacean behaviour, distribution, migration and reproduction. Each year, tens of dolphins die tragically, being incidentally caught in the commercial fishing gears.
In the coastal fishing performed on the Romanian littoral, both in shallow and offshore waters, many types of gears designed for passive and active fishing are used. They act in both coastal and offshore waters, using stationary and filtrating hauled gears. In the offshore fishery, the most widely used gears are mid-water trawl, turbot and spiny dogfish gillnets and spiny dogfish longlines. In the coastal fishery, the gears most used by the fishing enterprises are marine pound nets and gillnets.
The incidental catches of dolphins were caused by the fraudulent fishing practiced by Turkish vessels in the Romanian EEZ and through the intensification of the fishing effort carried out with gillnets and trammel nets by local fishermen. Most, if not all, recorded accidental catches of dolphins in gillnet gears involved the species
The most hazardous areas in relation to increased cetacean mortality are connected to the distribution of the turbot agglomerations and, implicitly, the distribution and size of the fishing effort (number of gillnets). An imminent threat to cetacean populations are abandoned or lost gillnets (as a result of observations, they remain functional and continue to retain individuals that they intersect).
According to information from economic agents practising specialized turbot fishing, on the Romanian coast the average number of dolphins accidentally caught by turbot gillnets with a mesh size of 200 mm, for a regular check (4-5 days, but conditional upon the weather), is 1-2 dolphins in 30-40 gillnets. When turbot gillnets show a higher number of by-caught dolphins, the main cause is that they are not checked in due time. More than 95% of entangled cetaceans, mainly of the species
How can this problem be solved?
- Increasing the awareness of sustainable exploitation by issuing legislation that is applicable immediately.
- Drawing up protection programmes on areas and periods, based on the behaviour of certain economically valuable species, mainly strongly correlated with stock evolution, and increasing the selectivity of fishing gear.
- Enhancing control in areas prone to poaching and discouraging access to these areas, as well as extending operations by creating joint inspection teams from the riparian countries.
- Improving communication in cases of spotting of IUU activities, followed-up by immediate penalties.
- Registering vessels/boats on IUU "black lists" and forbidding the right to operate for 3-5 years and, in case of relapse, permanently.