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The total catch of fish (excluding aquaculture) divided into: commercial fish catch (by species where possible), discarded catch, non-target landed bycatch and estimated recreational and subsistence catch. Expert assessments of the status of wild stocks of fish, crustaceans and molluscs. The harvesting of fish, crustaceans and molluscs from the marine environment is a major human activity affecting marine biodiversity. Total fish catch may give an estimate of the magnitude of pressure from harvesting biomass from the marine environment. Where management controls are effective, the mixture and rank of species in the top 20 will be relatively stable, or change very slowly, however, for some fisheries variation can be driven by environmental parameters. Stock assessments are available for some major commercial fisheries. Expert assessments are largely based on fish catch, adjusted for commercial effort, and population dynamics of the species involved. The consistency in ranking of the top 20 fish species in total seafood catch, particularly the high value fisheries of abalone and rock lobster, reflects a commitment to sustainable fishing practices and the comparatively low value of most finfish fisheries. The change in importance of some other species over time reflects the dynamic nature of some fisheries, with significant changes in management arrangements, the development of new fisheries or inter-annual variability. Zonation in the abalone fishery has been introduced to manage the distribution of effort, and protect easily accessible areas from high fishing pressure and over-exploitation. Stock assessment of blacklip abalone suggests a decline in two regions of the eastern zone, but populations in the western zone appear healthy with catch rates continuing to rise. The greenlip fishery in the Furneaux group has stabilised and stocks may be rebuilding. While the recreational catch of abalone is relatively small it is likely to be significant in more accessible areas. The west coast is particularly important to the rock lobster fishery with over 70% of the total catch coming from west coast waters. Stock assessment indicates an increase in Statewide catch rate, legal sized biomass and egg production. Current assessments indicate that further stock rebuilding is likely to occur if the total allowable commercial catch (TACC) is 1,500 tonnes but not with a TACC of 1,600 tonnes or higher. The increase in the number of recreational licences is of concern, as recreational effort tends to be concentrated on shallow accessible areas. The most important developments in the scalefish fishery since 1997-98 have been the significant increases in dropline, spear, dip net and squid jig effort. Squid jig effort had increased around one hundred fold over the reference period, reflecting increases in effort targeted at southern calamari and especially automatic jig effort targeted at arrow squid. Interestingly, effort levels declined for methods regulated through limited entry (e.g. purse seine, beach seine). Graball net effort declined markedly. The shift in effort to methods such as squid jig and dipnets reflects the introduction of management arrangements that primarily targeted the more traditional fishing methods, such as graball, purse seine and beach seine nets. The 1999-00 catch for banded morwong was lower than the minimum reference level and had declined by greater than 30% compared to the previous year. Catch and catch rate indicators demonstrate the impact of the fishery on the banded morwong population and suggest that the sustainability of the fishery, even at current levels of exploitation, is uncertain. The resource status for most scalefish fisheries is unknown. A survey of recreational gillnetting indicated that significantly more effort was expended by recreational fishers than commercial gillnet fishers. The survey found that recreational catches of several key species are significant and probably exceed the commercial catch. Daily logbook data, for fishery dependent assessments, is available for the majority of commercial fisheries. Fishery independent assessments are also conducted for rock lobster and abalone. Estimates of recreational fish catches are being undertaken. Annual stock assessments are conducted for abalone, rock lobster and major finfish fisheries. Catches of the two most valuable fisheries in Tasmania, blacklip abalone and rock lobster, consistently ranked within the top three in the total seafood catch between 1996 and 2000. This consistency is predominantly due to a commitment to sustainable fishing practices in these fisheries and the comparatively low volume and value of other fisheries, particularly finfish species. When open, the scallop fishery can contribute significantly to total seafood catch. However, there is a greater difference in the ranking of the other species. This can be partially explained by significant changes that have occurred in Commonwealth and State fisheries management arrangements since 1995 (e.g. shark, jack mackerel), the development of new fisheries (e.g. squid, calamari, live reef fish) and inter-annual variability (striped trumpeter), which have all contributed to changes in targeting and effort. Some fisheries that were previously managed within State waters by the State are now predominantly managed and assessed by the Commonwealth (e.g. shark, jack mackerel).
The abalone fishery targets blacklip abalone and greenlip abalone, with diving being the only commercial method allowed. Assessment of the fishery is based principally on an analysis of trends in the catch and catch-rate of the commercial fishery. This data is provided by licensed abalone divers on dockets submitted with all abalone landed. Catch and effort are reported for 48 statistical blocks, which are commonly grouped in to eight regions for analysis. Catch and effort data are not standardised and therefore include variations due to factors such as season, weather and diver experience. Recent assessments use catch-effort data supplemented by fishery independent data such as size and age composition In 2000, the abalone fishery was divided into separate fishing zones. The purpose of zoning was to manage the distribution of effort, and protect easily accessible areas from high fishing pressure and consequent over-exploitation. The fishery was divided into an eastern and western zone with a third distinct zone for the greenlip fishery. Each zone was given a fixed total allowable commercial catch (TACC). The introduction of zoning will change the way in which divers operate, making current assessment techniques that depend on catch information less reliable and comparisons with past management conditions less meaningful.
Early assessments of the abalone fishery tracked the movement of trends in catch and catch rate by block. However, due to considerable inter-annual variation that cannot reasonably be interpreted as change in abundance (even at a regional level), interpreting trends at block scale was discontinued. The 2000 stock assessment compares catch and effort with two reference periods. The first reference period (1979-82) featured unrestrained catches, while in the second period (1992-95) catches were subject to their highest level of constraint in regard to quotas and size limits. Statewide, blacklip abalone catches have increased 35% on the 1992-95 average. This increase was due to both an increase in the State TAC and a cap on greenlip catch, which shifted effort back into the blacklip fishery. In contrast, the 2000 blacklip catch is 17% less than the 1979-82 catch, placing it at an intermediate level between the two historical periods.
The 2000 assessment suggests that blacklip abalone stocks have declined in two regions of the eastern zone (east coast and south-east) with reduced catches and abundance in these two regions. Size distribution data indicates that the fishery in these two regions was substantially dependent on recruits and size limits may be too small to ensure adequate recruitment. The western zone blacklip fishery appears to be healthy with catch rates continuing to increase, indicating that stock levels are unaffected by the increased catch. The greenlip fishery in the Furneaux group has stabilised and stocks may be rebuilding, but increased catches in the north-east and north-west need monitoring. However, overall, the measure of abundance (raw catch-rates) is an unreliable indicator of abundance because of improvements in diver efficiency, and the inclusion of extraneous factors affecting the divers ability to collect abalone.
The number of recreational abalone licences increased from 4,151 in 1995-96 to 7,367 in 2000-01. Surveys of recreational fishing suggest the recreational abalone harvest in 1997 was approximately 37.5 tonnes (about 1.5% of the commercial harvest) (Lyle 2000). The data suggest that the recreational fishery focuses on blacklip abalone and that 70% of the recreational catch comes from the south-east and east coast. Surveys of recreational fishing in Tasmanian suggest that the recreational catch of greenlip abalone is relatively small (Lyle 2000). The recreational catch of abalone continues to represent a very minor proportion of the commercial catch. While the recreational catch is small overall it is likely to be significant in areas that are close to population centres. Recreational divers are also more likely to continue taking abalone from reefs where populations would be insufficient to maintain acceptable commercial catch-rates.
The Tasmanian rock lobster fishery targets the southern rock lobster, with the only commercial method allowed being rock lobster pots. Tasmania has jurisdiction over the fishery in waters generally south of 39°12', and out to 200 nautical miles from the coast. Fishers record their daily catch in degree blocks around Tasmania. Regional trends in the rock lobster fishery are assessed for eight regions around the State. The distribution of the 1999 catch clearly shows the current importance of the west coast (particularly areas five and eight), with almost 70% of the total catch taken from west coast waters. The fishery is assessed annually against defined reference points. Data from the 1999 assessment indicate increases in Statewide catch rate, legal sized biomass, and egg production relative to both the previous year and the reference year.
Catch rates in Tasmania remained relatively constant or increased during the 1970s and early 1980s prior to a decline to record lows in the mid 1990s. This has been followed by minor recovery, due largely to new management arrangements. Since the lows of the mid-90's, catch rates for 1999 showed considerable improvement, the exceptions being area one, which has remained static, and area eight which has shown a decline. These are non-standardised annual CPUE values so they will be influenced by the change to quota management. While the distribution of effort between regions appears relatively unaffected by the introduction of quota, there has been a shift in the seasonal timing of effort, with less expended during summer months and more in winter.
Data from 1999 assessment indicate an increase in Statewide catch rate, legal sized biomass, and egg production relative to the previous year and relative to the reference years. Increases in egg production, legal sized biomass and catch rates were due in part to unusually high levels of recruitment in the north-east of the State. Projections that assume more average patterns of recruitment indicate that further stock-rebuilding is likely to occur if the TACC is 1,500 tonnes, but not with TACCs of 1,600 or 1,700 tonnes.
Recreational catches of rock lobster are taken by potting, diving and with rings. Divers are permitted to use surface supply, scuba, and snorkel. Over half the recreational rock lobster catches are taken by potting. Effort is concentrated in shallow water of less than 18 metres, due to the constraints of safe diving and the ability to pull pots by hand. There has been a substantial and steady increase in the number of recreational licences issued over the last five years. Since 1996 pot and dive licences have increased by 40% and 43%, to about 9,700 and 4,800 licenses, respectively. This escalation in licenses is of concern and a survey is being undertaken to determine if the increased number of licences is reflected in an increased catch. Reasons for the increase in licenses include improved public awareness for the need for licences, increased police surveillance, the option to buy a second licence for a minimal amount and improved catch rates by recreational fishers. The use of rings did not require a license prior to 1999.
The commercial scalefish fishery is a multi-species fishery involving a wide variety of fishing methods. In addition, many scalefish species are important to the recreational fishery. An important element of the Scalefish Management Plan is the explicit identification of performance indicators (trigger points). Prior to 1995, fishers provided catch returns that were a monthly summary of catches, but were often incomplete in terms of detailing effort and gear information. These catch returns provided basic information about production levels but were of little value in providing a meaningful basis for catch per unit effort (CPUE) analysis. In early 1995, a new catch return was introduced that collected daily catch and effort information for each fishing method. Therefore, effort and CPUE information are presently only available for a five year period with the first three years (1994-95 to 1997-98) being used as the reference period to define the trigger points. In this regard there are only two years of data available to assess fishery performance. Annual fishery or species trigger points include:
The most important developments in the fishery since 1997-98 have been the significant increases in dropline, spear, dip net and squid jig effort. For all but squid jig, 1999-00 effort levels were between 10-40% higher than during the reference period. Squid jig effort had increased around one hundred-fold over the reference period, reflecting increases in effort targeted at southern calamari and especially automatic jig effort targeted at arrow squid. It is noteworthy that these methods are available to all holders of scalefish licences. However, in terms of days fished, only dropline and jig effort exceeded reference levels, suggesting that for the other methods that exceeded the effort triggers, more gear or time per day was spent fishing. By contrast, effort levels declined for methods regulated through limited entry (e.g. purse seine, beach seine). Graball net effort also declined markedly. The shift in effort to methods such as squid jig and dipnets reflects the introduction of management arrangements that primarily targeted the more traditional fishing methods such as graball, purse seine and beach seine nets. 1999-00 effort trigger point assessment, by major fishing methods Effort > 10% peak 1995-97 levels Method Gear units Days fished Beach seine N N Purse seine N N Graball net N N Small mesh N N Dropline (<200m depth) Y* Y* Handline N N Troll N N Fish trap N N Spear Y* N Dip net Y* N Squid jig Y** Y** Detailed species stock assessments (Lyle and Hodgson 2000) involving an examination of catch, effort and CPUE data have been conducted for striped trumpeter, banded morwong, sea garfish, wrasse, southern calamari and arrow squid. Catch, effort and CPUE trigger point analysis for key species are summarised in the Table. Summary trigger point assessment for key species - 1999-00. Catch Effort CPUE
Species
Outside 90-97 range
Decline/ increase by >30% Increase by >10% from highest 95-97 level
< 80% min. 95-97 range Striped trumpeter Y
+
N Y
#
N Banded morwong* Y
-
Y
-
N Y Sea garfish N N N N Wrasse** N N N N Southern calamari Y
+
N Y N Australian salmon N N N N Bastard trumpeter N N N N Blue warehou N Y
-
N N Flounder Y
-
N N N Jackass morwong Y
-
Y
-
N N Arrow squid Y
+
Y
+
Y N
The 1999-00 catch of striped trumpeter was higher than catches taken during the reference period. Particularly strong recruitment of 1993 and 1994 cohorts appears to have contributed significantly to this increase and indicators based on catch and effort are likely to be strongly influenced by recruitment variability. Handline catches have increased since 1995-96. Dropline and graball net catches fell slightly by comparison with 1998-99. CPUE for dropline fishing rose whereas graball catch rates fell. By comparison, CPUE for handline fishing has remained relatively stable over recent years. The triggers for total catch and handline effort for striped trumpeter were exceeded in 1999-00. The resource status is unknown.
The fishery for banded morwong expanded in the early 1990s with the development of live fish markets. However, the annual catch has declined steadily since 1994-95 due primarily to a large decrease in effort and recent declines in CPUE. Banded morwong are long-lived (up to 80 years) and productivity appears to be very low. In addition, the species demonstrates strong site attachment suggesting that it will be susceptible to localised over-fishing. Research and commercial catch sampling have indicated that there is size structuring within the population at small spatial scales, to the level of a particular reef. This suggests that assessment at fishing block and regional levels may not detect more localised changes in abundance. The 1999-00 catch was lower than the minimum reference level and had declined by greater than 30% compared to the previous year. As a consequence both catch triggers were exceeded. Declines in catch and effort were evident in most fishing blocks. Statewide and in most east coast regions catch rates declined to below 80% of the lowest reference level and therefore the catch rate trigger was also exceeded. Catch and catch rate indicators demonstrate the impact of the fishery on the banded morwong population and suggest that the sustainability of the fishery, even at current levels of exploitation, is uncertain.
The 1999-00 sea garfish catches declined slightly compared to the previous year but were within the reference catch range. The decline was due mainly to a fall in the dip net catch. Effort and catch rates in the dip net sector fell considerably but did not exceed the trigger level. Beach seine catch and effort has been relatively stable over the past three years while catch rates have increased in the past two years. However, sea garfish are a schooling species and catch rates are not considered to be reliable nor sensitive parameters for indicating trends in abundance. No triggers were reached for sea garfish in 1999-00. The resource status is unknown.
The development of live fish markets for wrasse has resulted in increased catches since the early 1990s. Although two main species are involved (purple wrasse and blue-throat wrasse) it is not possible to distinguish catches of individual species. Overall catch declined from 91 tonnes in 1998-99 to 85 tonnes in 1999-00, reflecting decreases in trap and handline catch and effort. CPUE decreased for all methods in 1999-00. Although wrasse are comparatively short-lived, attaining maturity well before they are recruited to the fishery, they demonstrate strong site attachment and therefore, assessment even at the smallest reporting scale (block level) may mask more localised changes in abundance. No triggers were exceeded for wrasse in 1999-00. The resource status is unknown.
The 1999-00 catch of southern calamari exceeded the maximum obtained over the 1990 to 1997 period, although catch was slightly less than in 1998-99. Jig effort continued to escalate, up by 25%, following a six-fold increase in the previous year. Evidence suggests that short-term closures of Great Oyster Bay in late 1999 were successful in providing some degree of protection to spawning squid. The closures may also have been partly responsible for the distinct shift in the dynamics of the fishery, with Mercury Passage contributing catch and effort comparable to that seen in Great Oyster Bay. Calamari have a life span of generally less than one year. Considering this, the accumulation of recruitment across a number of years is not possible, which results in considerable potential for inter-annual variability in abundance and vulnerability to over-fishing. Catch and effort (jig) triggers in 1999-00 were exceeded for the second consecutive year. The resource status is unknown and the sustainability of current catch levels is uncertain.
The catch of arrow squid in 1999-00 of over 430 tonne is the highest reported catch of the species from Tasmanian waters. It represents a five-fold increase in catch over the previous year with increased squid jig effort, primarily by automated jig vessels, accounting for the majority of the catch. The catch was concentrated off south-eastern Tasmania and in particular Storm Bay. Jig catch and effort triggers in 1999-00 were exceeded for the second consecutive year. The resource status of arrow squid is unknown and the sustainability of current catch levels is uncertain. The relationships between arrow squid populations from south-eastern Tasmania and those exploited in the Commonwealth fishery in Bass Strait is not known, yet it appears likely that it is a single stock.
Catch, effort and CPUE were also examined for blue warehou, Australian salmon, bastard trumpeter, flounder and jackass morwong. These parameters were within the reference criteria for Australian salmon and bastard trumpeter. The 1999-00 catch of blue warehou, although within the reference range, fell by over 30% compared with the previous year, indicating that the catch trigger was reached. Flounder and jackass morwong catches were also lower than during the reference period and jackass morwong catches fell by over 30% compared with the previous year. Effort and CPUE triggers for blue warehou, flounder and jackass morwong were not exceeded.
Since the introduction of licences for recreational nets in 1995-96, the number of licensed nets has generally increased from around 8,900 to a peak of over 11,000 in 1999-00. A Statewide survey of recreational gillnetting conducted between December 1996 - April 1998 indicated a total of 560,000 hundred metre net hours of effort was expended for a catch of in excess of 400 tonnes of scalefish. By comparison, commercial graball effort was around 314,000 hundred metre net hours, resulting in a catch of over 560 tonnes for the same period. Blue warehou dominated the recreational gillnet catch, representing about 45% of the total catch weight. Species of secondary importance included bastard trumpeter, Australian salmon, silver trevally and striped trumpeter. For several species the recreational component was significant in relation to the commercial gillnet catch. Therefore it is important that the impact of the recreational fishery is also taken into account in stock assessment. Comparison of catch and effort for recreational and commercial gillnet fisheries for key species. Based on the period December 1996 - April 1998. Gillnet catch (tonnes) Species Recreational Commercial Blue warehou 191.6 230.9 Bastard trumpeter 42.0 73.3 Australian salmon 28.3 27.5 Silver trevally 30.3 3.6 Striped trumpeter 22.4 28.6 Cod 14.7 7.9 Leatherjacket 12.4 4.7 Mullet 10.1 6.3 Wrasse 10.0 28.0 Jackass morwong 9.5 20.1 Flounder 8.5 18.7 Jack mackerel 7.1 5.4 Flathead 6.5 4.5 Banded morwong 1.8 105.8 Effort (100 m net hours) 560,160 314,170 Apart from gillnetting, there has been no comprehensive assessment of the recreational scalefish fishery to date. However, information about the fishing activity of recreational licence holders has been collected. Although available data do not include the activity of non-licensed recreational fishers, it was evident that species such as flathead, Australian salmon, barracouta and striped trumpeter are important to the line fishery while flounder are commonly targeted using spears (Lyle 2000). Based on incomplete fishery coverage (i.e. licensed fishers only), the estimated flathead and barracouta catches both exceeded 100 tonnes for the period December 1996 - April 1998. Catches of 10-30 tonnes were estimated for Australian salmon, cod, striped trumpeter and jackass morwong during the same period. These findings indicate that recreational catches of several key species are significant, probably exceed the commercial catch. The 2000-01 national recreational fishing survey will provide for a more comprehensive assessment of recreational catch and effort. ANZECC Core Indicator (Estuaries and the Sea) |
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