• An Atlas of Fishing and Some Related Activities in Ireland's Territorial Sea and Internal Marine Waters with Observations Concerning their Spatial Planning

      Fahy, E.; Healy, E.; Downes, S.; Alcorn, T.; Nixon, E. (Marine Institute, 2008)
      This Atlas was initiated as part of Ireland's preparation for the Water Framework Directive (WFD) which, inter alia, required mapping the distribution of mobile fishing gears in coastal waters (inside 1 n mile outside the base lines). The Atlas subsequently expanded the geographical extent of the review out to 12 n miles. The history, descriptive terminology and extent of subdivisions of the territorial sea are provided. The Atlas is a collection of 1,885 polygons showing the distribution of fishing and fishery related activities, including aquaculture and mariculture within the Republic of Ireland's territorial sea and internal marine waters. The Atlas demonstrates that the greatest range and intensity of fishing and related activities are undertaken in the internal waters of the State. Hook and line fishing emerged as the most widely used metier and a combined array of mobile gears, ranging from pelagic otter trawls to hydraulic dredges, took second place. The total area occupied by fishing and fishing related activities was just under 125,000 km2. The principal metier groupings within 12 n miles were: hook and line occupying 57,000 km2 (45% of the total), mobile gears (towed enclosing nets and dredges) accounting for 27,530 km2 (22%). Passive nets (static tangle and gill nets and the now defunct salmon drift nets) made up 18,000 km2 (14%). Pots targeting crustaceans and molluscs occupied 13,250 km2 (11%). Aquaculture and mariculture occupied 172 km2, some 0.4% of the area within 12 n miles. To supplement the polygons, a table of metier and species combinations in internal and territorial waters opposite each county with a long shoreline is supplied. The table includes fisheries whose existence is known but not their extent. The consequences for benthic community structure of the use of a particular metier, the purpose of the exercise for the WFD, are considered. "Community" refers to fish or invertebrate species assemblages. Applications for the data are discussed in the context of a growing appreciation of the need to plan the use of inshore waters for fishery conservation and to accommodate a wide range of stakeholder interests and to embrace the ecosystem approach to maritime governance. Difficulties inherent in conserving fish species rather than biological communities are illustrated by reference to a case history. Data presented in the document were sourced from the tacit knowledge of stakeholders. Planning jurisdiction in the Republic of Ireland is described with reference to inshore waters. Recent thinking by fishery commentators is reviewed. Finally, current thinking on inshore spatial planning within the EU and particularly among our nearest neighbours is discussed and the possibility of implementing ICZM is briefly considered. This document is presented as Version 1 of a continuing exercise. Governmental departmental arrangements and collected data refer to the period up to 2006. The Atlas should be periodically revised as more information becomes available.
    • Bionomics of brown crab Cancer pagurus in the south east Ireland inshore fishery

      Fahy, E.; Hickey, J.; Perella, N.; Hervas, A.; Carroll, J.; Andray, C. (Marine Institute, 2004)
      The south east inshore brown crab fishery is delimited by the boundary of longitude - 6.3, within a coastal band of approximately 18 km (10 nm) in width and it extends along the south coast of Co Wexford for a distance of approximately 55 km; evidence for the stock extending into the inshore fishery west of the Waterford Harbour estuary is sparse. The fishery, whose maximum extent is calculated at 427 km2, yielded up to 700 t per year during the 1990s. In 2002 annual landings of 959 t accounted for 8.2 % of the national catch. The average overall LPUE was 0.87 kg per pot lifted in that year. Brown crab were landed whole or as claws, for human consumption, and clawed or, of poorer quality, with claws, to provide bait for the whelk fishery. This fishery is not considered to have any discard of legally sized crab and, in consequence, a large percentage of the landings is poorly conditioned. The stock is intensively fished; the amount of gear in use increased almost 5 fold since the mid 1970s. Landings per boat declined since the late 1980s although this may be as a result of sharing among a greater number of vessels. In 2002 an estimated 60 - 69 vessels fished brown crab in the peak autumn months. In 2002 and early 2003, 3,674 crabs were tagged in the inshore fishery; of these 14.4% were recaptured (12.8% of tagged females and 20.7% of tagged males). Observations made during tagging operations in 2002 only were used to clarify sex ratio and the incidence of recently moulted animals. The crab stock consists of a migratory female component which moves into shallow waters during the summer months probably to moult and mate. The male component is more sedentary. Both sexes move at speeds which slow during the summer months and increase again as the year advances; maximum speeds of 2 km/day were recorded for both sexes in the autumn. Movements by male crab were random while females adopted a south west trajectory. The greatest distance recorded for a tagged female crab was 136 km after 287 days at liberty. Other tagged females, reported by French vessels, were recaptured in ICES division VIIg which may be the over-wintering area for the stock. These animals had moved between 69 and 75 km from their release point. Tag reporting by the industry is considered to have been low. Based on the 'rate of tag recovery, the estimated rate of exploitation was lower than expected in an intensely fished stock. Population estimates were attempted using the Petersen formula and on the basis of assumptions about mortalities which recognized the phenomena of moulting and migration. The south east crab stock moves with the current which is westerly along the southern Irish coast. Recorded migrations were also short when compared with those of brown crab in the northern stock and in several other documented fisheries. The Nymphe Bank which adjoins the south east fishery has a water current pattern which retains larvae and it is known to have a high density of brown crab in the plankton. The existence of retaining currents may make the kind of long migrations which characterise others unnecessary for this stock. The status of the south east fishery is not known. LPUE indices provided by the Roscoff super-crabber fleet for ICES statistical division VIIg remained fairly stable between 1987 and 2002 but the quantity of crab captured by those vessels has declined considerably in most years since 1995.
    • The commercial exploitation of shrimp Palaemon serratus (Pennant) in Ireland

      Fahy, E.; Gleeson, P. (Marine Institute, 1996)
      Palaemon serratus is at the northern limit of its range in the British Isles. In Ireland it is most abundant in the southwest where it has been commercially fished since the mid-1970s. Landings in recent years have averaged between 200 and300 tonnes annually with an estimated export value of £2—3 m. These landings represent a three-fold expansion over those of the previous decade. The biology of the species was investigated over a 12 month period in Bantry Bay using commercial gear. At most times of the year there is a bimodal length frequency distribution and the life expectancy is interpreted as 2 years. Condition factor does not vary much during the year in males and immature females but the larger females put on up to 30% weight in the autumn. The reproductive cycle in Bantry resembles that in the south of England rather than that in north Wales, these two locations providing earlier studies of the species. The largest females come into berry in October and egg carriage within the population continues into the following summer; in May, a second group of smaller females, belonging to the 0 age group, carries eggs. Corroborative evidence for this interpretation is provided by the size of the ova and their developmental state. There would appear to be an influx of shrimp to Bantry Bay which builds up from May and declines after January but cohort and gender migrations are unclear. Catch per unit of fishing effort (cpue) is estimated from the weight of a consignment of shrimp delivered to a processor. Such data are variable but they are also consistent and stable over the short-term and throughout the range of shrimp fisheries. A time series from 1977 to 1994 suggests a 36% decline; the significance of this is not known. Shrimp fishing takes place during the autumn and winter months. In the southeast landings are taken throughout the year but those outside the period August to January, inclusive, do not exceed 8% of the total. In the southwest only 3% of landings are made outside these months, while in Connemara none was reported Mechanical grading in the factory is explored as a means of reconstructing age profiles. Two patterns of exploitation are described: that of the southwest and southern coast has a larger proportion of 0 group shrimp which may reach 40% by numbers of the total landings; in Connemara the proportion of 0 group shrimp is much smaller. Attempts are made to find some method of predicting aspects of the catch from biological and sea temperature data. There is a suggestion that a large brood year is influential in producing a successor whose size is estimated 2 years later. The sustainability of the shrimp fishery is unknown and two precautionary measures are suggested as the basis of a management regime: enlarging the mesh size to improve the exploitation pattern and limiting the fishing season.
    • Distribution, population structure, growth and reproduction of the razor clam Ensis arcuatus (Jeffreys) (Solenaceae) in coastal waters of western Ireland

      Fahy, E.; Norman, M.; Browne, R.; Roantree, V.; Pfeiffer, N.; Stokes, D.; Carroll, J.; Hannaffy, O. (Marine Institute, 2001)
      Samples of razor clams, Ensis arcuatus, the species which makes up the majority of landings from the west coast of Ireland, were collected by commercial fishery methods, in association with the dredge fishery and by scuba diving, from three locations off the coast of Co Galway. E. arcuatus occupies coarse sand (of maerl and shell fragments) and rarely co-exists with the other common species of the region, E. siliqua. E. arcuatus were aged, an age-length-key devised for them, and growth parameters (Linf, k and t0) were calculated. Their maturation state was established by histological examination. Evidence suggests that Ensis arcuatus is mainly a spring spawner, although some spawning appears to take place in most months, with a spatfall in June/July. Maturation commences in its third year. Asymptotic length is achieved at 10 years, approximately, and there was little variability in growth among the three sampling areas or between the sexes. In a small bed of razor clams in Cill Chiarain Bay, Co Galway, there would appear to have been a spatfall in most, if not all, of the past 15 years. The quantitative distribution of E. arcuatus in a single bay within the boundaries of Comharchuman Sliogeisc Chonamara Teo, Co Galway, was estimated by divers salting quadrats of 0.33 m2. The razor clam community is divided into a generally distributed fraction occurring at low density (described as the non-bed) and at a relatively higher density (described as the clam bed). The bed was situated in the lee of reefs, which is usually the case for this species along the Atlantic seaboard. More than 90% of the biomass was above the E.U. minimum size limit.
    • The Dundalk Cockle Cerastoderma edule Fishery in 2003-2004

      Fahy, E.; Carroll, J.; Murran, S. (Marine Institute, 2005)
      A cockle fishery in Dundalk Bay has been infrequently documented since 1970. Cockle bearing sands and muds are 44.5 km2 in extent. The bay, which is in an SPA and a cSAC also supports large numbers of overwintering birds, of particular relevance is the oystercatcher (Haematopus ostralegus). In 2003 and 2004 when an assessment of the fishery was undertaken, cockles ranged from 0 to 8+ years of age, but the vast majority were 0 and 1+ animals. Growth was rapid and 53% of asymptotic length (49.1 mm) was achieved at the first winter. In agreement with observations elsewhere, the density of the rapidly growing animals was very low. The estimated cockle biomass in spring 2004 was 1,654 tonnes comprising 143 million animals. A survey undertaken in spring 2004, suggested that spat falls contributing to the population may not have been evenly distributed throughout the Bay. Condition factor in 2003 and 2004 did not conform to an expected seasonal pattern, suggesting that some parts of the area supported better growth rates than others. Cockle landings from this fishery are of good quality. Cockle size is at the upper end of the range in Britain and Ireland and the majority of individuals landed by suction dredging were 1+ years old. Raked landings contained more 2+ cockles than suction-dredged ones. Damage to cockles discarded by suction dredging followed the pattern reported elsewhere and damage rates increased with the size of the animals. Some cockle landings have probably always been made in Dundalk Bay by picking and raking, but 2001 marked the beginning of an expansion of the dredge fishery, whose landings exceeded 200 tonnes in 2004. The necessity for controls and management of this fishery in the context of EU legislation and particularly within the constraints of the Habitats Directive is briefly examined.
    • Fishery Associated Changes in the Whelk Buccinum undatum Stock in the Southwest Irish Sea, 1995-2003

      Fahy, E.; Carroll, J.; Hother-Parkes, L.; O'Toole, M.; Barry, C. (Marine Institute, 2005)
      The whelk fishery of the southwest Irish Sea had a turnover of approximately €18 million and employed 250 people directly and indirectly in catching and processing in 2003. In the nine years, 1995-2003 inclusive, whelk landings to Ireland from the southwest Irish Sea fluctuated between 3,800 and almost 10,000 tonnes(t) per year; from an estimated 5,000 – 15,000 boat-days annually. A collapse in landings was recorded in 1997 and again in the spring of 2004. The fishery is divided for assessment purposes into four sectors, the central two consisting largely of nursery area and the north and south extremities of the fishery populated by more older, larger and mature whelk. Logbooks were not completed by fishermen participating in this fishery which was, in theory, managed by size limit, but the regulations were not enforced. Boats fishing whelk made daily fishing trips and daily weights recorded by processors were used to estimate biomass in each of the sectors by depletion regressions. Total biomass fluctuated between 12,720 t in 1999 and 37,319 t in 2002. The estimates based on a full season’s landings are used to compare the fishery from one year to the next and to supply weighting factors for other parameters of the population. Exploitation rates were lowest in one of the central sectors of the fishery (where they averaged 27% annually). At the southern extremity they averaged 39%. Depletion estimates based on landings records from approximately April to 15 June provided higher exploitation rates and lower biomass. The mortality coefficient Z, calculated from a catch curve, peaked in two years, 1998 and 2002, as did an index of recruitment. The age at full recruitment declined after 2000. Throughout nine years of documented history, one of the central sectors of the fishery assumed progressively greater dominance over the others, providing 77% of the landings from the entire fishery to its ports in 2003. Some sectoral changes to the whelk population may be irreversible: the oldest animals have been removed from the northern extremity of the fishery and while the whelks which are exploited at the southern end between 2000 and 2003 were similar in size to those exploited in the mid-1990s, their tonnage between 1999 and 2003 decreased from 47 to 4% of the landings in 1995. A substantial recruitment in 2001 or 2002 was followed by an increase in fishing effort of 42% between 2002 and 2003 and this is identified as the reason for the collapse in 2004.
    • The inshore pot fishery for brown crab (Cancer pagurus) landing into south east Ireland: estimate of yield and assessment of status

      Fahy, E.; Carroll, J.; Stokes, D. (Marine Institute, 2002)
      Although it is regarded as an important focus of brown crab Cancer pagurus landings, the fishery in south east Ireland is poorly documented and the official statistics are believed to under-record the species by a factor of 2-3. This appraisal of the south east Ireland brown crab fishery is based on >22,000 records of sales transactions from the 1990s and a comparison of the biological characteristics of landings in the late 1960s with thirty years later, in the context of increasing fishing effort. The three buyers who gave access to their books inwards for periods of the 1990s, purchase from the same fishing community and they compete for product but they occupy slightly different market niches: a vivier truck operator exports to Spain, a processor concentrates on autumn purchases of female crab for vacuum packing while the third buys crab claws for human consumption and crab bodies which are used as bait for whelk Buccinum undatum. Only the first sales of crab from 55 km of coastline are considered. In this area fishing effort doubled between 1972 and 1988 but expansion accelerated in the following decade by at least 128%; a single operator increased his effort by 80% between 1988 and 1998. In the 30 years after 1968, the number of pots per km of coastline rose by 241%.The sale of brown crab is recorded in consignments which are raised to live weights in the analysis. Consignment size fell steeply in the late 1980s and early 1990s after which it stabilised; adjusting the figures to allow for increasing effort accentuated the trend; at the same time consignment number rose. Allowing that a decline in consignment size was accompanied by an increase in pot number, consignment number should have risen by 310% to maintain landings at the level recorded in 1990; the largest recorded increase in consignment number was by 230% and while it is accepted that all sales transactions have not been obtained, it is likely that LPUE has been declining over the 1990s in real terms in this fishery. Increasing fishing effort during that time is seen as a product of better technology, stimulated by a desire to compensate for falling LPUE. Comparison of size and sex composition of the landings recorded in the late 1960s and the late 1990s are inconclusive. Depth of water and type of substratum are likely to influence the composition of inshore landings. An argument is presented that the south east inshore crab fishery is fully or over-exploited. It is likely to have an offshore component and such occasional data as are available on brown crab further south suggest that the offshore is an under-exploited fishery. In which case, the rate of interchange between the two components is likely to be crucial to the continued performance of the inshore fishery
    • The Maharees spider crab Maja squinado fishery in 2000

      Fahy, E. (Marine Institute, 2001)
      A pot fishery directed on spider crab (Maja squinado) grew out of a mixed tangle net and pot fishery for large crustaceans in the early 1980s. Approximately twenty half decked vessels of 10m in length have been involved for the duration of the fishery but the numbers of pots per vessel has increased; currently 10,000 pots are set for spider crab in Tralee and Brandon Bays during the summer months. Cpue rose initially during the early years of the fishery, then it stabilised and declined although in the late 1990s it again recovered somewhat. Sampling in 2000 suggests that the size composition of the catch has altered since the early years of the fishery, its main consequence being the removal of the older age groups so that the landings now consist almost entirely of a single year class. Aspects of the biology of the Maja squinado are compared with what is already known of the species and a number of recommendations are made for the future management of the fishery. These include a further increase in the size limit, a ban on tangle nets and a cap on fishing effort.
    • Observations on the status of bass Dicentrarchus Labrax stocks in Ireland in the late 1990s

      Fahy, E.; Forrest, N.; Shaw, U.; Green, P. (Marine Institute, 2000)
      Investigative work was undertaken in 1996 to ascertain the strength of sea bass stocks following the introduction of a range of conservation measures which effectively extinguished the legitimate commercial fishery for the species. Information was sought from two sources: estimation of the age composition of the samples and the growth of bass by examining scales from exploited fish. An estimate of the density of juvenile pre-recruit bass was made from a seine net survey undertaken in various estuaries along the south coast. Scales sent in by anglers and obtained through the regional boards from illegally netted fish indicate that a high proportion of bass landed between 1996 and 1998 belonged to the 1989-year class, which had been reported to be exceptionally large in Britain. Back-calculations of length-at-age from the scales of these and seine-netted bass suggested that growth improved in the later 1980s in response to higher sea temperatures but has since declined. Work on an index of juvenile abundance began with 59 seine net hauls made in August 1996 and 1997. On these the areas most likely to support bass were characterised; O-group bass were encountered more frequently than any other age group. Sites most likely to support bass were mud flats overlaid with shallow and still water which had a salinity range of 17 to 22% and bass were associated with certain species of estuarine fish and crustaceans; bass were negatively associated with other species occupying the deeper and more sandy parts of estuaries. Sampling stations for O-group bass have been selected in Youghal Harbour and Wexford Harbour. Further exploratory work is required to extend the list of stations. It was concluded that there has been a temporary increase in the numbers of sea bass, as has been reported by fishermen in Ireland, as a result of more favourable temperatures in the late 1980s. Growing conditions appeared to have deteriorated in the later 1990s and the summer growth ofO-group bass was the weakest in 1999 over the 4 years investigated. A time series of O-group abundance is too brief to permit any conclusions to be reached. However, it can be stated that the recorded densities of juvenile bass between 1996 and 1999 were sparser than would be expected in south east Ireland in view of the supposed heavy winter concentrations of the species in the Celtic Sea.
    • A second assessment of the whelk fishery Buccinum undatum in the southwest Irish Sea with particular reference to its history of management by size limit

      Fahy, E.; Masterson, E.; Swords, D.; Forrest, N. (Marine Institute, 2000)
      Whelk landings in the southwest Irish Sea increased from 56 t in 1990 to 6,575 t in 1996 after which they stabilized between 3,600 and 4,600 t annually. At its peak the fishery supported approximately 80 vessels but this number has halved since. In 1994 a size limit of 50 mm was introduced for conservation purposes. Age based assessments of the landings were carried out in 1994, 1996, 1997 and 1999, for which purpose the fishery, ranging from 52º10’ to 53º30’, is divided into four sectors. Landings to the four sectors display biological characteristics which indicate the occurrence of a number of stocklets rather than a single stock unit. Whelk in the south west Irish Sea are relatively thin shelled and the fishery has a low density of large crustacean predators. There is no evidence of contamination by TBT. The northern and southern ends of the fishery have relatively lower densities of larger/older animals; the centre sectors have smaller whelk of shorter life span at higher densities, some of them showing symptoms of a Lee phenomenon and slower growth. A survey of cpue places heaviest densities on the Codling and Rusk Banks, in strong tidal currents, at depths of < 20 m. Growth and maturation rates vary among stocklets. L∞ ranges from 102 to 116 mm. Length at 50% male maturation is usually within the range of 63 – 68 mm and ages of 6.1-7.2 years although landings to one sector have a 50% male maturation rate of 83 mm and 8.5 years of age. The existing size limit of 50 mm would, at best, afford protection to 40% of spawning males. Compliance with the size limit has been poor. From 20 to 33% of total landings in any of the assessed years have been less than the legal limit and in 1994 51% of landings in one sector were below the acceptable size. Trends in cpue have been monitored since 1990 and some areas do not show any marked tendency. On the contrary, some fishermen in the centre sectors improved their yield between 1994 and 1998. There are two explanations for this: the movement of pots onto virgin ground and the fact that fewer fishermen are competing for landings in the same areas. Whelk have responded to a reduction in fishing effort since 1996 immediately following which mortality coefficients (Z) were highest (0.79); they declined to an average 0.61 in 1999. In terms of yield per recruit however they remain high. The southern sector of the fishery is regarded as being most depleted although very few subsize limit whelks were caught there. The survival of the whelk fishery in the southwest Irish Sea is attributed to the instability of the market which is dominated by a single customer, South Korea. A more effective size limit for this fishery would be 68mm (83 mm in the northern sector) and this is considered unrealistic, suggesting that alternative management measures will have to be considered.