MINISTRY OF AGRICULTURE, FISHERIES AND FOOD CSG 15 Research and Development Final Project Report (Not to be used for LINK projects)
Two hard copies of this form should be returned to: Research Policy and International Division, Final Reports Unit MAFF, Area 6/01 1A Page Street, London SW1P 4PQ An electronic version should be e-mailed to [email protected]
Project title Archiving and analysis of the MBA bottom trawl and benthic survey data: Unravelling fishing efforts from climate change
MAFF project code MF0727
Contractor organisation Marine Biological Association of the United Kingdom, The Laboratory, and location Citadel Hill, Plymouth. PL1 2PB.
Total MAFF project costs £ 64,600
Project start date 01/11/00 Project end date 31/03/01
Executive summary (maximum 2 sides A4)
Marine ecosystems can alter dramatically over our lifetimes through natural processes or human activities such as fishing, pollution, recreation and coastal development. At present, the factors driving long-term change are poorly understood. A major area of concern is the impact of climatic fluctuations. Over the last twenty years, sea surface temperatures in the English Channel have risen by on average 1ºC, and a global rise in SST of over 1ºC is predicted over the next fifty years. There is convincing evidence that such climatic change can significantly affect populations and distributions of marine species, but to date there is little evidence for changes in demersal fish and invertebrate assemblages within European waters. These communities, important from both economic and ecological perspectives, are however known to be heavily impacted by fishing. Since the onset of commercial trawling, fishing techniques have become increasingly efficient. The effects on many target species have been well studied, but far less is known of the wider impacts on non-target fish and benthic invertebrates. The consequences of climatic change and commercial fishing pose significant national environmental problems to fishery scientists, aquatic resource managers, conservationists and policy makers alike.
Only by comparing contemporary resurvey with baseline information within long-term datasets can change be identified. The Plymouth Laboratory of the Marine Biological Association (MBA), founded in 1888, has collected and archived long-term records on a range of variables from the English Channel and Western Approaches over the last century. Data include the composition of planktonic, intertidal and benthic/demersal communities, and measurements of temperature and nutrients. This project is focussed upon MBA long-term demersal fish and benthic invertebrate datasets that have previously resided predominantly in archived notebooks. Primary objectives were to catalogue, archive and enter records onto modern databases, assess their ability to enable us to understand causes of long-term change in marine communities and conduct preliminary analyses to determine whether change has taken place.
Demersal fish. The groundfish assemblage off Plymouth has been sampled intermittently between 1913 and 1986. All information from these surveys, including species abundance and length measurements, have been entered onto a CSG 15 (Rev. 12/99) 1 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
database. Resurveys of historic sampling sites have been conducted between January and March 2001, and an ongoing monthly trawl survey has been initiated at station L4 (50°15’N 4°13’W). A summary of the details of the demersal fish database has been placed on the MBA website demonstrating the extent of this archive. Upon request access to the dataset will be granted to interested parties. Details of the archive have also been included in the database of historic trawl records recently compiled by CEFAS Lowestoft within MAFF project MF07-028.
Results demonstrate that there have been major changes in the composition of the demersal fish assemblage since 1913, and these changes are consistent with major, ecosystem-level, impacts of fishing identified by analogous studies elsewhere. Mean lengths of fish (Lavg) has shown significant decline, indicating a reduction in the proportions of larger individuals in the community. There were also declines in mean maximum length (Lmax) and mean length of maturity (Lmat) of the assemblage, suggesting a species-level switch to taxa that grow to, and mature at, smaller sizes. In a second level to these analyses, taxa in the community were divided into commercially and non-commercially exploited subgroups. Declines in means of Lavg, Lmax and Lmat were most apparent in commercially exploited taxa. We also detected evidence for significant decline in the mean trophic level of the assemblage. Analyses of community diversity showed no significant changes over time in either species richness, or abundance-based taxonomic diversity (D) or taxonomic distinctness (D*) indices, but significant declines the presence-absence based taxonomic distinctness index (D+), suggesting that closely-related groups are of taxa have declined simultaneously in frequency of occurrence. Taken together, evidence is consistent with patterns expected from the selective, unsustainable harvesting of large, commercially valuable species from high trophic levels. We suggest that means of Lmax, Lmat, trophic level and taxonomic distinctness (D+) may be suitable indices for assessing the impact of fishing on multi-species demersal fisheries.
We found little evidence for direct effects of changes in sea-surface temperature on the composition of the groundfish assemblage. Effects of climate change may be difficult to determine on a local scale, due to both climate- and fishery- induced impacts on density dependent natural ecological processes such as competition and predation. Hence, although climate does not appear to necessarily cause direct responses on local population abundance, change may be detectable at the regional scale. Future work is required to examine the effects of broader geographic scale on detecting climate- induced change, in order to determine whether changes in species abundance and/or presence-absence of demersal taxa can be reflective of climatic variability. While we have been unable to detect local-scale changes in fish community structure that have resulted from climate change this does not mean they have not occurred. The detection of factors that operate on a geographic scale is best accomplished using a broad-scale sampling programme.
Benthos. The benthic invertebrate fauna of the English Channel were sampled extensively between 1959-85 by the late Dr Norman Holme. Data have largely resided in notebook form or as appendices to publications. These data have been catalogued and archived within the National Marine Biological Library in Plymouth, and assessed for the quality of the data and the potential for re-survey. Three datasets were identified. 1) a quantitative faunal record of echinoderms and molluscs for 324 stations distributed throughout the length and breadth of the English Channel. Other taxa are recorded qualitatively. Sampling was conducted using an anchor dredge that samples both epi- and infauna. In addition Holme compiled references to, or data from comparable historic MBA surveys as far back as 1895. 2) brittlestar survey; mostly quantitative records of all echinoderms from 329 stations on the south coast of England using a mini-Aggasiz trawl, a technique that samples epifaunal more efficiently than infauna 3) death assemblages; a full record of all dead-shell material retained in anchor dredges was made. In addition an extensive archive of videotapes (106), videocassettes (59) and photographic transparency (90 rolls) has been catalogued. The video surveys were made using a towed camera sled. These visual records have been examined and vary in quality, transparencies being far superior to videos. These records can be used to record the presence or absence of larger species and give useful information for habitat mapping.
Conclusions and future R&D. These archived demersal fish and benthic invertebrate records are a unique resource within the United Kingdom and Europe with which to investigate long-term changes in demersal ecosystems. Both sets of records form baselines to compare with contemporary resurvey, and enable effects of fishing to be examined, and potentially once appropriate models are developed, climatic change. Results of analyses conducted to date on the demersal fish dataset demonstrate clear patterns of temporal change, there is need to further investigate the patterns demonstrated. We plan a further project / projects in conjunction with CEFAS Lowestoft, to continue to analyse historic data, to continue monitoring the demersal fish assemblage off Plymouth, to resurvey some of Holme’s benthos sampling stations within the English Channel and determine the importance of disturbance and geographic scale in studies long- term change.
CSG 15 (1/00) 2 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Scientific report (maximum 20 sides A4)
1 Project Background 1.1 Introduction……………………………………………………………………………………….. 4
2 Demersal Fish 2.1 Description……………………………………………………………………………..………… 5 2.2 Specific Objectives……………………………………………………………………………….. 6 2.3 Summary of achievements………………………………………………………………………… 6 2.4 Potential for resurvey and analysis……………………………………………………………….. 7 2.5 Data analysis……………………………………………………………………………………… 7 2.5.1 Seasonal trends………………………………………………………………………… 7 2.5.2 Inter-annual changes in assemblage composition……………………………………… 8 2.5.3 Inter-annual changes in species abundance ……………………………………….….. 9 2.5.4 Inter-annual changes in total number of fish caught………………………………….. 9 2.5.5 Inter-annual changes of community mean length …………………………………... 10 2.5.6 Inter-annual changes in community life-history parameters……………….………….. 10 2.5.7 Inter-annual changes in community trophic level…………………………………….. 10 2.5.8 Inter-annual changes in diversity indices……………………………………………… 11 2.5.9 Community change in relation to climatic fluctuations……………………………….. 12 2.6 Summary and context of results…………………………………………………………………... 12 2.6.1 Detecting fishery induced change……………………………………………….………… 12 2.6.2 Detecting climate induced change………………………………………………………… 13
3 Benthos 3.1 Introduction……………………………………………………………………………………….. 13 3.2 Objectives…………………………………………………………………………………………. 13 3.3 Summary of achievements…………………………………...……………………………………. 13 3.4 Dataset – seabed species…………………………………………………………………………... 13 3.4.1 Description………………………………………………………………………………... 13 3.4.2 Potential for resurvey and analysis……………………………………………………….. 14 3.5 Dataset – brittle-star survey…………………………………………………………………….…. 14 3.5.1 Description………………………………………………………………………………... 14 3.5.2 Potential for resurvey and analysis……………………………………………………….. 15 3.6 Dataset – death assemblages………………………………………………………………………. 15 3.6.1 Description………………………………………………………………………………... 15 3.6.2 Potential for resurvey and analysis……………………………………………………….. 15 3.7 Videotape, videocassettes and photographic transparencies archive…..……….………………… 15 3.7.1 Description………………………………………………………………………………... 15 3.7.2 Potential for resurvey and analysis……………………………………………………….. 17 3.8 Summary and context of results…………………………………………………………………... 17 3.8.1 Overview………………………………………………………………………….………. 17 3.8.2 Detecting fishery induced change……………………………………………….………... 18 3.8.3 Detecting climate induced change……………………………………………….……….. 18 3.8.4 Conclusions and recommendations……………………………………………………….. 18
4 Final conclusions and recommendations …………………..………………………….…………….. 19
5 References……………………………………………………………………………….…………….. 19
Annex 1 Vessels employed on MBA standard hauls 1913-2001 ..……………………..………………….. 21 Annex 2 Number of demersal fish hauls 1913-1986…………….…………………………………………… 22 Annex 3 Mean duration of demersal fish hauls 1913-1986 ..…………………………...…………………... 23 Annex 4 Number of hauls during each month 1913-1986………..……………...…………………………. 24 Annex 5 Details and characteristics of species in demersal fish hauls 1913-2001…………………………. 25 Annex 6 Fluctuations in annual abundance of demersal fish species 1913-2001…….……………………… 28 Annex 7 Temporal abundance and length trends of demersal fish species 1913-2001……………………… 32 Annex 8 Regressions of sea-surface temperature and species abundance of demersal fish 1913-2001.…….. 34 Annex 9 GIS Representation of Holme benthos sampling sites……………………………………………… 36
CSG 15 (1/00) 3 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
1 Project Background
1.1 Introduction
The problem. Marine ecosystems can alter dramatically over our lifetimes through natural processes or as a result of human activities such as fishing, pollution, recreation and development. The consequences of these changes can lead to national environmental problems of interest to fishery scientists, aquatic resource managers, conservationists and policy-makers alike. Evidence would suggest that inshore demersal ecosystems are particularly vulnerable to change from impact by commercial fisheries (Jennings & Kaiser 1998). While the disturbance effects of fishing have been well studied in commercial species, less is known about impacts on the non-commercial fish and benthos, or their current conservation status. Climatic change can cause distributional and abundance changes in marine organisms, but disentangling them from the effects of high intensity commercial fishing activity can be difficult (Hall 1998).
Effects of fishing. Levels of exploitation of fish and shellfish stocks within European waters have increased dramatically during the last century (see for example Fig. 1), and it is estimated that heavily fished grounds may now be trawled more than five times per year (Rijnsdorp et al. 1998). Most stocks are now either fully or over-exploited (Botsford et al. 1997), with some on the verge of economic extinction (Cook et al. 1997), recovery after decline is usually a very slow process (Hutchings 2000). While the effects of fishing on target species are subject to intensive research, the ecosystem and community-level effects of fishing have only recently begun to be understood (Hall 1998). A technique of quantifying change is to compare historic with present day assemblages, either in single historic-contemporary comparisons, or with use of time-series. Analyses using such methods have demonstrated that abundance and size-spectra of many commercially targeted species have declined over the course of the 20th Century, consistent with predictions of impacts of fishing (Rice & Gislason 1996, Walker & Heessen 1996). Furthermore, it has been demonstrated that life-history traits can predict which populations or species are likely to be impacted by fishing (Jennings et al. 1998). Typically, larger slower growing and less fecund species are more likely to decline in abundance than smaller, faster growing and more fecund relatives (Jennings et al. 1999, Dulvy et al. 2000).
The study of long-term effects of fishing disturbance on the benthic invertebrate fauna is relatively novel, but it is known that trawling can modify physical habitat characteristics (Hall 1998), and can cause dramatic reductions in the abundance of many benthic invertebrates (Jennings et al. 2001). Again, behavioural and life-history characteristics render some species susceptible to trawling damage, with larger species tending to suffer highest levels of mortality (Jennings et al. 2001). Fisheries-induced shifts from communities dominated by large vulnerable epifaunal, to assemblages dominated by small-bodied infauna have been documented (Kaiser et al. 2000).
200000 Fig. 1 – Effort of trawlers in the English Channel 1919- 160000 Sail 1990. Inefficient sail-power was gradually replaced Steam before the outbreak of the 120000 Motor second world war by steam and motor powered 80000 vessels. Post-war, the hours fished by motor 40000 trawlers have steadily increased. Annual hours fishing 0 Data from MAFF annual 1910 1920 1930 1940 1950 1960 1970 1980 1990 sea fisheries statistics. Year
Effects of climate change. The English Channel is in a faunistic transition zone between cold (boreal) waters and warmer southern (Lusitanian) waters. There has been a rise sea surface temperature of over 1ºC over the last 20 years (Figure 2), and climate warming scenarios predict further rise of 1.4-5.8ºC over the next century (Schneider 2001). The ecosystem-level effects of future change can only be speculated upon, but modification of both pelagic and demersal communities may result. For example climatic correlates of cod (Gadus morhua) recruitment have recently been demonstrated (O’Brien et al. 2000), and there is substantial evidence that climatic change has driven changes in the pelagic ecosystem off the south-west England during the 20th Century (Southward et al. 1988). Herring (Clupea harengus) used to be the major subject of a fishery in Plymouth until the 1930s when the fishery collapsed and was replaced by pilchard (Sardina pilchardus). This has been attributed to broad ecosystem-level changes in response to regional climatic warming (Southward 1980). Fish have well-defined temperature preferences and there is some evidence that climate-induced temperature changes can redefine the latitudinal range of demersal fish communities (Murawski 1993, Gomes et al. 1995, McFarlane et al. 2000), but, detecting change within ecological assemblages is not always straightforward (Hall 1998). The responses of organisms to climate change will be determined by a complex system of physiological responses that in turn influence both behaviour
4 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
and the balance of density-dependent ecological interactions such as competition and predator-prey relationships (Davis et al. 1997). Hence, climatic fluctuations may not necessarily lead to direct changes in numerical abundance at the local scale.
13.5 Fig. 2 – Sea surface temperature within grid square 50-51º N, 4-5º W (off Plymouth). 13 1871-2000. Trendline 6th order fitted polynomial. 12.5 Data source: UK Meteorological Office Hadley Centre / British 12 Atmospheric Data Centre.
Hadley data correlate well with temperature (ºC) 11.5 MBA sea surface temperature records from ICES station E1
Mean annual sea surface 11 (50º02’ N, 4º22’ W). r = 0.84. 1860 1880 1900 1920 1940 1960 1980 2000
Year Datasets. In order to examine patterns of change in marine ecosystems, the Marine Biological Association has collected and archived records on range of variables from the region of the English Channel and Western Approaches over the course of the 20th century. Data include the composition of planktonic, intertidal and benthic/demersal communities and measurement of temperature and nutrients (e.g. Southward & Boalch 1993; Maddock & Swann 1977, Southward & Butler 1972, Southward 1980). These records provide an opportunity to examine patterns and causes of long-term community-level change. The project focussed upon the MBA long-term demersal fish and benthos data sets that, until now, have resided predominantly in notebook form. The primary objective of this project was to catalogue, archive and enter these records onto modern databases, and to assess their potential to enable us to understand long-term change in the benthic ecosystem and to propose a strategy for future research and development.
Project direction. This five-month MAFF-funded first phase of the project has been a ‘proof of concept’ study to retrieve and archive demersal fisheries and benthos long-term datasets. Within this phase, change was examined in the composition, mean length, life- history traits and diversity of the fish assemblage, with a view to developing indices of fishing pressure. Community-level effects of fishing and fluctuating sea surface temperature were investigated and potential explanations forwarded. Recommendations are made for further study. Benthos data were evaluated to assess analytical potential. As a result, a proposal for further analysis and re-survey has been prepared jointly with CEFAS Lowestoft to commence 2002-2003, subject to the outcome of a bid to MAFF in open competition.
Value of project. It is widely recognised by fisheries scientists, conservationists and regional policy makers that it is important to understand the causes of change in the marine ecosystems, from economic, sociological and conservation perspectives. The significance of this project is that it has enabled evaluation of the quality and usefulness of long-term fisheries-independent datasets that might otherwise have been neglected. The MBA demersal fish dataset is particularly valuable as it represents an independent source of information on effects of fishing on demersal fish communities, encompassing all species, not just target species for which landing data are routinely collected. These data will be of use in the future in the development of quantitative indicators that will enable us to disentangle the effects of fishing from climatic variability. Overall, this project has completed it’s major objectives (stated in subsequent sections), and has helped us to progress in developing informed views of both natural and anthropogenic effects on the marine environment.
2 Dataset – demersal fish
2.1 Description
A total of 687 MBA standard hauls were conducted between 1913-1986 on inshore waters around Plymouth (Annex 2), an area that has been heavily fished from fishermen from Looe and Plymouth throughout the course of the last century. Six vessels have employed (Annex 1). Hauls were on average 60 minutes duration (Annex 3), and catches were sorted and the number of individuals of each finfish taxa in each haul were recorded. The only incomplete abundance records were between 1967 and 1975 where numbers of poor cod (Trisopterus minutus) and dragonets (Callionymus lyra) were not recorded, only presence/absence. In most cases species-level identification was performed, but in some years, and with some species groups identification was only undertaken to genus or family- level, leaving a total of seventy taxonomic groupings (Annex 5). In addition to counts, many specimens were measured for total length from hauls post 1919, providing the opportunity to examine changes in assemblage size-spectra over the course of the 20thC.
5 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Sampling was throughout the year, but tended to concentrate on more clement summer / autumn months June to October (Annex 4). Historically, the most comprehensive seasonal sampling was undertaken between 1953 and 1957 with RV Sula at ICES station L4, (grid square N12, Fig. 3). Data from this period represent the best subset with which to examine seasonal species abundance trends. With some caveats (see section 2.4), the dataset appears to be an internally consistent assessment of the demersal fish community of inshore waters off Plymouth and provide a baseline on which to assess future change. The time-series is not complete, but nevertheless these records comprise one of the best long-term datasets on a whole fish assemblage present within the UK.
4°30’ W 4°15’ W
³ 100 trawls
³ 10 trawls Plymouth
³ 1 trawls Looe
Polperro 50°20’ N
R Rame Hd
Q Yealm Hd
P
O
N 50°15’ N M
L
K
J
I 50°10’ N 96 97 98 99 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Fig. 3 – Distribution of historic MBA trawls 1913-1986. Most trawls have taken place at ICES station L4 (50°15’N, 4°13’W), grid square N12.
2.2 Specific objectives:
· Extract existing bottom trawl data and compile onto PC-based databases · Conduct a resurvey of selected fishing grounds for which historic data is available · Prepare a report to MAFF, in conjunction with a publication in JMBA on long-term change in fish assemblages off Plymouth
2.3 Summary of achievements
All data have now been entered onto spreadsheets. A summary of the data is posted on the MBA website (http://www.mba.ac.uk). and a series of preliminary analyses have been conducted to determine the broadscale patterns of change in the community. To date twenty-two hauls have been conducted, resurveying historic MBA sampling sites. These data have been incorporated into the following analyses (section 2.5). Publications on long-term and seasonal changes in the Plymouth demersal assemblage are to be submitted for peer review in the foreseeable future.
6 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
2.4 Potential for resurvey and analysis
The value of the MBA demersal fish records is that they are from hauls at recorded locations on known dates. There is clear potential for resurvey and analysis. However the following points need to be considered and addressed before and during analysis and resurvey.
Fishing vessels and gear. Six vessels have been used during the trawl survey and in each case it is likely that they differed in their efficiency due to vessel power, gears and slight variation in trawling techniques used by crew. However we can be confident that the 2001 re-surveys are comparable with surveys conducted on RV Squilla from 1974 onward, as the same gear has been operated by some of the original crew members. Information on gears used by the vessels historically has not been located within archives, but details of those routinely used by SS Oithona, RV Sula and RV Sarsia have been taken from publications (Annex 1). Due to the paucity of notes on gears used and information on tow speeds, we have been unable to standardise catch rate data from different vessels for swept areas per unit time, and instead have based quantitative analyses on the perhaps over simplistic CPUE index of catch (individuals) per hour. Given that small species are present within all years (e.g. scaldfish - Arnoglossus spp.), we are confident that use of a small-mesh cod end has been consistent.
Locations: The location where trawls were shot between 1913 and 1919 were noted down using the bearing between landmarks, these were subsequently plotted onto Decca Navigator charts, and superimposed by a grid (Figure 3). Due to limitations in navigation technology during these early periods, the locations given can be at best estimations. Historic sampling has been conducted on two main sampling areas with slightly different habitat characteristics, the Rame-Eddystone (including ICES station L4) and Looe grounds, both of which have bottom depths of approximately 50 metres. They are known to have different substrate characteristics and benthic invertebrate faunas (Marine Biological Association, 1957), which are likely to influence demersal fish fauna. The Rame- Eddystone ground is characterised by two types of grounds firstly coarse grounds with a bottom soil of muddy gravel and secondly fine grounds with a bottom soil of muddy sand. The grounds are very patchy, and the two typical benthic faunas are intermingled, so that in short hauls species from both types of bottom soil are obtained. The Looe grounds are characterised by fine sand and gravel with outcroppings of rock. Further research is needed to examine this fine-scale spatial differences in species composition.
Seasonality: Strong seasonal differences of the fish fauna have been identified within the years 1953-57 (Section 2.5). However hauls have not always been performed on a monthly basis, hence there are potentially confounding effects of seasonality on inter-annual trends. In the following preliminary analyses, we have examined broad-scale trends, but future resurvey should repeat sampling on a monthly basis to make more accurate temporal comparisons.
Length measurements: Total length was measured in most hauls between 1919 and 1986, however some species such as the lesser- spotted dogfish (Scyliorhinus canicula) have not been consistently measured. Furthermore, where subsamples were taken we can only assume that selection of specimens was random. Disc widths of skates and rays were measured, hence it has been necessary to convert these data to total lengths using known conversion factors.
2.5 Data analysis
Broad-based analyses of general trends in the species composition of the assemblage were examined. To remove variability caused by sporadic large catches of pelagic species analyses have focussed solely on demersal species (Annex 5).
2.5.1 Seasonal trends
Many marine fish have well defined breeding seasons and migration patterns (e.g. Hyndes et al. 1999). In order to determine if seasonal changes in demersal fish abundance should be considered during future re-sampling campaigns, trends were examined with the historic dataset. The most seasonally comprehensive trawls were taken between 1953-57 hauls at ICES station L4 . Clear species- level seasonal changes in numerical abundance are evident from these data (Figure 4). Nearly all of the fifteen numerically most abundant taxa demonstrated some evidence of seasonal changes in abundance. Two-way ANOSIM analysis (Clarke & Warwick 1994) was applied to the whole assemblage (Year x Season; Jan-Mar, Apr-June, July-Sept, Oct-Dec, no data transformations), significant differences were present both between the years (R = 0.372, p < 0.001) , and between seasons (R = 0.303, p < 0.001). Hence, there is convincing evidence that seasonal community-level shifts in species abundance take place in this assemblage. Potential causes of change include 1) movements of species from their nursery areas into deeper waters, 2) seasonal migrations to spawning areas, 3) temperature related movements governed by physiological restrictions and 4) seasonal movements following food sources (Hyndes et al. 1999). In some species, such as plaice (Pleuronectes platessa), lemon sole (Microstomus kitt), flounder (Platichthys flesus) and dab (Limanda limanda) it is known that inshore spawning aggregations of some flatfishes occur in spring, thereby explaining a higher abundance (e.g. Rijnsdorp et al. 1992), but to fully understand these patterns, an integrated study of and inshore and offshore seasonal sampling needs to be undertaken, incorporating seasonal abundance, length-distributions, diet and spawning condition.
7 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Trisopterus minutus Scyliorhinus canicula Merluccius merluccius
1200 30 10 1000 25 8 800 20 6 600 15 4 400 10 200 5 2
Mean catch per hour 0 Mean catch per hour 0 Mean catch per hour 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Month Month Month Callionymus lyra Zeus faber Pleuronectes platessa 600 25 15 500 20 400 15 10 300 10 200 5 100 5 Mean catch per hour Mean catch per hour 0 0 Mean catch per hour 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Month Month Month Arnoglossus spp. Raja / Leucoraja spp. Phrynorhombus spp. 150 10 5 8 4 100 6 3 4 2 50 2 1
Mean catch per hour 0 Mean catch per hour 0 Mean catch per hour 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Month Month Month Limanda limanda Chelidonichthys cuculus Callionymus maculatus 150 30 8 25 6 100 20 15 4 50 10 2 5
Mean catch per hour 0 Mean catch per hour Mean catch per hour 0 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Month Month Month Merlangius merlangus Microstomus kitt Mullus surmuletus 100 12 12 80 10 10 60 8 8 6 6 40 4 4 20 2 2 Mean catch per hour Mean catch per hour 0 Mean catch per hour 0 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Month Month Month
Figure 4: Seasonal changes in the abundance of the 15 dominant taxa: Average abundance in hauls during each month 1953-58. Trendlines 3rd order fitted polynomials. Of these taxa nearly all shown some indication of seasonal differences in abundance.
2.5.2 Inter-annual changes of assemblage composition
To date many published analyses demonstrating long-term community-level change in species composition have relied upon a single comparison of historic with contemporary resurvey (e.g. Greenstreet & Hall 1996, Rogers & Ellis 2000). The multiple sampling occasions within the MBA Plymouth survey makes it possible to examine changes through time with finer resolution. Annual mean CPUE and frequency of occurrence within hauls each year were calculated for each species. Frequency of occurrence reduces the dominance of the common species, and enhances the contribution made by the numerically less abundant taxa in multi-species analyses. Similarity matrices of all years were constructed using the Bray-Curtis coefficient. The differences between years were graphically illustrated using the ordination technique of non-metric multi-dimensional scaling (MDS), and to determine if there has been a clinal change in community composition, the significance of relationship between time (difference in years) and community similarity were tested using the RELATE procedure in PRIMER (Clarke & Warwick 1994), a permutation test that removes the effects of temporal autocorrelation.
Analyses demonstrated substantial and significant shifts in the composition of the demersal fish assemblage off Plymouth between 1913 and 2001. A clinal pattern was evident within the MDS plot, the most recent years being clustered away from the earlier years (Fig. 5). The temporal change was significant for the whole assemblage (both transformations p < 0.001), and in commercial and non- commercial subgroups (Annex 5, data not shown, all comparisons p < 0.01) The correlation coefficient between annual community similarity and difference in time was higher with frequency of occurrence data (Fig. 5), indicating that there has been less change in comparative abundance of common species than the presence or absence of rare taxa. Interestingly, the data points from the resurveys conducted in 2001 are closely situated to the those of the 1950s indicating that in terms of species composition, contemporary
8 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
assemblages are remarkably alike to those of the last warm period. Similar inter-annual MDS patterns were present in analyses using seasonal subsets of the data (results not shown), providing evidence that the trend was not an erroneous outcome due to variability in sampling season.
Figure 5 – Long-term a) b) community level change 1986 100 1913-2001. a) MDS plot 1953 1956 19571958 1976 1954 2001 80 using annual mean 1955 19511952 1983 1950 CPUE. b) Relationship 1913 1978 60 1985 1979 1977 1920 between community 1919 40 1921 similarity using annual 20 1984 1922 mean CPUE and time community similarity (%) 0 between years r = 0.31. 0 20 40 60 80 100 Time between sampling (years) c) MDS plot using 1914 annual frequency of Stress: 0.07 occurrence within hauls d) Relationship between c) d) community similarity using annual frequency 1953 100 1956 of occurrence and time 1913 1954 1957 1958 1921 1950 1955 80 1952 between years r = 0.60. 1951 2001 1920 60
1919 40 MDS plots: closer 1985 points, represent more 1983 20
1979 community similarity (%) similar species 1978 1986 0 1977 1984 1922 0 20 40 60 80 100 assemblages.
1976 Time between sampling years 1914 Data from years 1967- Stress: 0.13 75 were removed from these analyses as abundance of all taxonomic groups were not quantified.
2.5.3 Inter-annual changes in species abundance
In order to determine the species-level trends analogous to the observed clinal change in assemblage composition, regressions of mean annual CPUE and annual frequency of occurrence against year were performed (Annex 8). Species with consistent increases in abundance over the course of the last century included lesser-spotted dogfish (Scyliorhinus canicula), cod (Gadus morhua), blue whiting (Micromesistius poutassou), ling (Molva molva), red bandfish (Cepola macrophthalma), plaice (Pleuronectes platessa). Species showing declines included spurdog (Squalus acanthias), megrim (Lepidorhombus whiffiagonis) and the streaked gurnard (Chelidonichthys lastoviza) (all r2 ³ 0.20). Species with consistent increases in frequency of occurrence included whiting (Merlangius merlangus), blue whiting, poor cod (Trisopterus minutus), ling , hake (Merluccius merluccius), red bandfish, cuckoo wrasse (Labrus mixtus), red mullet (Mullus surmuletus), dab (Limanda limanda), plaice and thickback sole (Buglossidium luteum). Species demonstrating declines included spurdog, streaked gurnard and the boarfish (Capros aper)(all r2 ³ 0.20).
2.5.4 Inter-annual changes in total numbers of fish caught
In heavily disturbed faunas, shifts occur from assemblages dominated by smaller numbers of large taxa, to communties with larger numbers of small taxa (Clarke and Warwick 1994). Hence, in addition to examining changes in size-spectra, it is useful to examine changes in the number of individuals caught per unit effort. The RELATE procedure in PRIMER revealed there had been a significant increase in the number of fish caught per hour in hauls since the turn of the century (RHO = 0.189, p = 0.017, Figure 6). This was heavily influenced by an increase of two orders of magnitude in the abundance of non-commercial species (RHO = 0.187, p = 0.027), in comparison numbers of commercial species showed no significant increase (RHO = 0.129, p = 0.095).
9 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
4 a 3 b 4 c 3.5 3.5 2.5 3 3 2 2.5 2.5 2 1.5 2 individuals per hour individuals per hour individuals per hour 1.5 10 10 10 1 1.5 Log
Log Log 1
1 0.5 0.5 1910 1930 1950 1970 1990 2010 1910 1930 1950 1970 1990 2010 1910 1930 1950 1970 1990 2010 Year Year Year
Figure 6 – Changes in numbers of individuals caught each year. a) all species; b) commercial species subset; c) non-commercial species.
2.5.5 Inter-annual changes of community mean length
Fisheries systematically remove large slow-growing individuals from assemblages (Rice & Gislason 1996). Hence, as an index of fisheries disturbance it is possible to calculate the mean length of the assemblage, with lower vaues predicted in more heavily impacted communities. The mean total length of many taxa changed during the study (Annex 7), and species were not always measured in each year. To overcome these problems, the mean total length value used for each species in each year was taken from a linear regression equation. In cases where a species was measured in less than five years this was a less accurate technique and instead the overall mean of all individuals was used. From these values, the average total length for all individuals, of all species, caught in each year was calculated (Lavg), and the significance of the change in time examined using RELATE. Analyses were performed upon the whole assemblage and the non-commercial and commercial species subgroups. There was a significant decrease in the mean total length of individuals within the assemblage of approximately 5cm during the study period (RHO = 0.136, p = 0.045, Fig. 7c). There was no significant trend in the mean lengths of the non-commercial subset (RHO = -0.036, p = 0.614), but the commercial species subset demonstrated a significant decline (RHO = 0.231, p = 0.02).
Species showing consistent declines in mean total length included the starry smooth hound (Mustelus asterias), cod, haddock (Melanogrammus aeglefinus), blue whiting, dover sole (Solea solea) and boarfish. Species showing consistent increases included lesser spotted dogfish, conger eel (Conger conger), greater pipefish (Syngnathus acus), gobies and flounder (Platichthys flesus)(all r2 ³ 0.20).
2.5.6 Inter-annual changes of community life-history parameters
Major changes in the community-based life-history parameters have been found in heavily fished groundfish assemblages of the North Sea (Jennings et al. 1999). To determine if similar trends were present in the Plymouth demersal fish community, trends in maximum length (Lmax) and length at maturity (Lmat , the total length at which 50% of the stock attain maturity) were examined. The Lmax and Lmat for each species were extracted from the global fish information database FishBase (Froese & Pauly 2001; Annex 5). These values were used to describe temporal trends in life-history parameters by calculating a mean value for all individuals, of all species, caught in each year, and examining the correlations of these values with time. Analyses of the life-history traits of whole community revealed a significant decline in mean maximum length (RHO = 0.174, p = 0.033. Fig 7b) and mean length of maturity (RHO = 0.261, p = 0.005, Fig. 7c). The commercial species subset also showed a shift in the mean length of maturity (RHO = 0.183, p = 0.026), and maximum length (RHO = 0.241, p = 0.014), while the non-commercial subset showed no significant trends in either length of maturity (RHO = 0.06, p = 0.253) or maximum length (RHO = 0.094, p = 0.137).
2.5.7 Inter-annual changes of trophic level
The mean trophic level of commercially fished assemblage has declined is globally (Pauly et al. 1998), and it has been suggested that this value can be used as a univariate index of the health of multi-species fisheries (Pauly et al. 2001). We examined changes in mean trophic level of the Plymouth demersal fish fauna, by calculating an average trophic level of all individuals of all species each sampling year. Estimates of the mean trophic level of each species were extracted from Fishbase (Froese & Pauly, 2001 – Annex 5). Relate analyses demonstrated that mean trophic level of the whole assemblage has significantly declined between 1913 and 2001 (RHO = 0.144, p = 0.035, Fig. 7d). The non-commercial species subset demonstrated an almost significant increase (RHO = 0.134, p = 0.058), and the commercial subset a non-significant decline (RHO = 0.059, p = 0.24).
10 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Fig. 7. a) Long-term change in mean 35 a) 80 b) length of the fish within the Plymouth groundfish assemblage Lavg; b) Change 30 70 in mean maximum length Lmax; c) Change in mean length of maturity Lmat; 25 60 d) change in mean trophic level. All
(cm) comparisons significant p < 0.05
20 50 max L Length (cm) 15 40
10 30 1900 1920 1940 1960 1980 2000 2020 1900 1920 1940 1960 1980 2000 2020
40 c) 3.8 d)
35
3.7 30 Level (cm)
mat 25
L 3.6
20 Trophic
15 3.5 1900 1920 1940 1960 1980 2000 2020 1900 1920 1940 1960 1980 2000 2020
Year Year
2.5.8 Inter-annual changes of diversity indices
Diversity indices are used to convert complex multivariate species abundance data into a univariate format. Traditional diversity indices designate each species to be a single unit, each as distantly related phylogenetically and ecologically to each other. However, communities are composed of subgroupings of closely-related individuals/species that act ecologically as similar units, and share similar behavioural or life-history traits. It is known that some species groupings are more susceptible to the impacts of fishing than others (e.g. Dulvy et al. 2000), while other taxa proliferate under these conditions, perhaps because benthic disturbance enhances available food resources. Traditional diversity indices would not always be able to detect these changes. To overcome this problem, taxonomy-based diversity indices have been developed. These indices have high values where there is a reasonably even spread of individuals/species from the total regional species list in an environment. However, if some closely-related species from some phylogenetic lineages are consistently absent, or conversely some are unusually abundant, low values of taxonomic diversity are generated. Hence, we can use taxonomy-based indices to determine the temporal effects of fishing. A phylogeny of the fish assemblage was constructed using information from FishBase (Froese and Pauly 2001) and included five taxonomic levels (Fig. 3). Three biodiversity indices described in Clarke & Warwick (1998) were used:
· Taxonomic Diversity (D), average path length between any two randomly chosen individuals in a sample, including from the same species. · Taxonomic Distinctness (D*), average path length between any two randomly chosen individuals in a sample, as long as they are not from the same species. · Taxonomic Distinctness (D+), average path length between any two randomly chosen species in a sample.
The weighting of each phylogenetic path length in this study was 1, so a value of 0 was chosen for two individuals of the same species, 1 for individuals of different species, but the same genus, 2 for individuals of the same family, but different genera etc. Further information on the use of these indices is provided in Rogers et al. (1999). In addition Hill’s N1 and N2 indices were included for comparative purposes. For these analyses the diversity was calculated for each haul, and the mean value taken for the year. Again, analyses of trends with time were analysed using the RELATE test in PRIMER that removed temporal autocorrelation.
Where the analyses were applied to the whole community, no significant changes in diversity over time were apparent using the traditional diversity indices (Hill’s N1 or N2 – data not shown), in taxonomic diversity D (p = 0.550), or taxonomic distinctness D* (p = 0.407) There were however significant declines in diversity in the presence-absence based taxonomic distinctness index D+ for the whole assemblage, and the commercial assemblage (both p < 0.05), but not the non-commercial assemblage (p = 0.534).
11 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code * a) b) + c) D 70 90 D 84 D
60 82 80 50 80
40 78 70 30 76 Taxonomic Diversity 20 60 74 Taxonomic Distinctness Taxonomic Distinctness 1910 1930 1950 1970 1990 2010 1910 1930 1950 1970 1990 2010 1910 1930 1950 1970 1990 2010 Year Year Year
Fig. 8 - Changes in annual mean taxonomic diversity and distinctness in the Plymouth inshore demersal fish assemblage 1913-2001.
2.5.9 Changes in the abundance of species in relation to climate
We examined community composition to determine if broad-scale community level change was detectable in the dataset in relation to fluctuating sea surface temperatures. Species were categorised into broad groupings Northern (median distribution > 50°N), English Channel-Biscay (median distribution 43-50°N), and Southern (median distribution <43°N). The mean CPUE of individuals belonging to each if these categories was calculated for each year. Similarly the total number of species represented by these distributional categories. These values were then correlated with mean annual sea-surface temperature for the sampling year, and the previous year, and the two previous years. There were no significant relationships present. In order to determine if there were any species specific relationships, the mean annual sea-surface temp of the two previous years were regressed against species abundance and frequency of occurrence (Annex 8). Species that demonstrated consistent positive abundance (CPUE) trends with temperature including poor-cod (Trisopterus esmarkii), nurse hound (Scyliorhinus stellaris), lesser spotted dogfish, lesser weever (Echiichthys vipera), and brill (Scopthalmus rhombus). Species demonstrating negative abundance trends were megrim (Lepidorhombus whiffiagonis) and the boarfish. Species demonstrating strong positive trend correlations of frequency of occurrence with temperature were angel shark (Squatina squatina), lesser weever and brill, while species with negative trends included cuckoo wrasse (Labrus mixtus) and megrim.
2.6 Context of results
2.6.1 Detecting fishery-induced change
These analyses suggest that there have been major community-level changes in the Plymouth demersal fish assemblage between 1913 and 2001. We have demonstrated many interrelated changes that are consistent with predictive models of impacts of fishing, and replicate results of studies of other temperate demersal fish assemblages. Temporal reductions in mean length (Lavg), mean maximum length (Lmax), mean length at maturity (Lmat), trophic level and taxonomic distinctness index (D+) of the whole community were found, and were also present in the commercially valuable species subset, but not within the non-commercial assemblage. Furthermore small non-commercial species have increased dramatically in abundance, but not the large commercial taxa, a pattern symbolic of a heavily disturbed community. Research on species and population-level responses to fishing pressure suggest that fisheries impact on larger, slow growing taxa (Jennings et al. 1999), properties that are pronounced in target demersal fish. This is exemplified in the Plymouth dataset by the dramatic reduction of the abundance of spurdog (Squalus acanthias), a species that was common prior to the 1920s and the subject of a major fishery, but is large and takes over 15 years to reach sexual maturity. In comparison the lesser-spotted dogfish (Scyliorhinus canicula) has steadily increased in abundance throughout the last century. This dogfish matures in under four years, has very little commercial value and individuals caught are usually returned to the water alive. There is no reason to suggest that natural variability would produce the suite of community-level patterns observed, as similar patterns have been demonstrated in other communities for size-spectra changes (Greenstreet & Hall 1996; Rice & Gislason 1996), trophic levels (Pauly et al. 1998; 2001), Lmax / Lmat (Jennings et al. 1999) and D+ (Rogers et al. 1999). The evidence is consistent with hypotheses of cumulative community-level changes in response to fishing pressure. Given the importance of life-history in determining the potential impacts of fishing on a species, it is possible that community-level changes in mean Lmat , Lmax, trophic level and D+ may be useful indices to provide a rapid assessment of the health of a fishery. These will need to thoroughly tested on a range of fish communities.
12 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
2.6.2 Detecting climate-induced change
Major changes have occurred in the sea-surface temperature since 1913. Notably a warming toward a peak during the 1950s, followed by decline in the 1970s and subsequent warming over the last 20 years. Complexity of processes leading to change in marine assemblages means that it is difficult to experimentally test community-level responses to climatic variability. Therefore it is necessary to compare evidence of faunal distribution patterns and abundances with environmental datasets (Southward et al. 1995). We found no major community level faunal changes that could be directly related to changes in mean annual sea-surface temperature. There were however some species whose abundances seemed reasonably well-linked with temperature, suggesting these may be climate indicator species. Climatic change is more likely to act as an indirect underlying driver of ecosystem-level change, rather than affecting all organisms directly in a similar manner. The response of communities may be complicated by a host of factors. Species- level responses to climatic change are likely to be strongly influenced by life-history characteristics, for example differences in breeding strategies (broadcast spawning with planktonic larvae vs. demersal egg laying), growth rates and seasonal migrations (potentially temperature driven) as well as the sensitivity of larval forms to environmental change. Furthermore climatic change may influence physiology and behaviour, processes that in turn may influence the outcomes of density-dependent ecological processes such as competition and predatory-prey interactions (Davis et al. 1999). The complexity of climate-influenced may lead to considerable variability in assemblages at the local scale, but it is possible that this may be ironed out over larger geographic scales, but further analyses and resurveys to determine appropriate sampling scales to detect change need to be undertaken. Given we possess comprehensive seasonal species abundance data collected during the 50s, it may be profitable to conduct monthly resurvey to examine possible temperature-related changes in seasonal fish migration, for evidence suggests that squid migration phenology is significantly affected by climatic change (Sims, Genner, Southward & Hawkins submitted to Nature).
3 Benthos - the Norman Holme archive
3.1 Introduction
The benthos are organisms living on or in the sea bed and includes both demersal fish and the organisms on which they feed. They have long been studied in fisheries science and over the past the past forty years benthic animals have been much used to indicate the extent of changes in the ocean resulting from disturbance or pollution. As many species are small in size and have limited mobility when faced with adverse environmental conditions they must either adapt or die. As a consequence, variation in the relative abundance of benthic organisms and in their patterns of distribution can be used as indicators of change.
3.2 Objectives
The study aimed to identify and catalogue material held by the Marine Biological Association from the sampling programmes and towed sledge surveys undertaken by Dr Norman Holme. It was intended to:
· Evaluate the quality of material, especially videotapes and photographs; · Assess the suitability of data sets for statistical analysis · Link archived notes to videotapes and photographs; · Recommend what further work should be undertaken to make use of material · Identify what future survey might be necessary.
3.3 Summary of achievements
Objectives of this section of the study have now been achieved and additional progress has been made mapping Holme’s sampling sites using GIS, enabling the spatial scale of surveys to be illustrated (Annex 9).
3.4 Datasets – Seabed Species
3.4.1 Description
Most of Holme’s data have been published and full records supporting his papers are lodged in the archive. The largest raw data set comes from Holme’s survey of the English Channel (Holme 1961, 1966). The intention of these substantial papers was not to describe community structure in detail but rather to map the distribution of dominant species enabling discussion of underlying biogeography. Species identified were mainly molluscs and echinoderms, data on other taxonomic groups were generally less complete. Nevertheless, provided that samples contain more than 30 individuals modern statistical techniques of community analysis may be employed. With smaller samples biogeographic studies remain possible. Offshore areas of the English Channel were further investigated using towed video and still cameras by Holme & Wilson (1985).
13 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Data are available for a total of 324 stations distributed throughout the length and breadth of the English Channel. Published papers provide latitude and longitude as well as Decca Navigator co-ordinates for each station. Only a small number of stations have replicate data. For each location there is a quantitative faunal record of echinoderms and molluscs. Other major taxa tend to be recorded without taxonomic precision and, at best, semi-quantitatively. Holme (1961) emphasises that his aim was “to provide the fullest qualitative evaluation of the fauna”. Archive records for each station are recorded on one or two sheets of paper. While annotations on record sheets show that some data have been entered into the MBA database of field survey records prepared by A.J. Southward, it is unlikely that all have been input.
In almost all cases during the English Channel survey, sampling was undertaken using a modified anchor dredge with a fine mesh bag inside a 12.7mm courlene net. Modification was to prevent the dredge from digging into the sediment too deeply and thus the sample taken integrates large bodied infauna with some epifaunal species. However, between publication of the two papers Holme changed his sample processing technique with a greater emphasis being placed on examination of a sub-sample of fine material sieved through a 2.2mm sieve. Holme (1966) describes his method as “rough and ready”.
Long-term change: Holme was interested in long-term changes and collected data from earlier benthic ecologists. He made a point of re-survey at historic sites. Notebooks contain references to or data (mainly molluscs and echinoderms) from the following locations:
· Veryan Bay (1959, 1981 1983) · Looe Ground (Veevers) 1950, 1951,1970, 1971, 1974, 1980, 1981. · Eddystone Amphioxus Gravel (Allen, Ford and Smith). 1895, 1922, 1931, 1950, 1951, 1970, 1971,1973,1975. · In addition to the Looe Ground and Eddystone stations, other stations sampled by Allen (1899) were re-sampled in the 1950s and 1970s.
Mollusc collection: A collection of mollusc shells was found among Holme’s effects. Although shells have been kept in cabinets and biscuit tins that are in poor condition both mollusc shells and labels are in a good state. Many specimens are of species that are comparatively rare and which few people who undertake routine identification will have encountered. Keys to mollusc identification are unsatisfactory and there are few expert molluscan taxonomists in UK. For these reasons, the shell collection is an extremely valuable resource. The collection is not just valuable as a source of named specimens, it tells us names that Holme gave (rightly or wrongly) to animals that he identified. In any re-survey of Channel biodiversity this collection is invaluable.
3.4.2 Potential for resurvey and analysis
Holme’s data could be re-analysed using modern, multivariate techniques. It is unlikely, however, that such re-analysis would reveal new and fundamental insights into distribution patterns of benthic assemblages in the Channel. It is highly probable that it would demonstrate far more subtle trends within well-known species assemblages. Dr Mike Kaiser (University of Bangor) has already undertaken some re-analysis of molluscan data in the MBA database but his findings have yet to be published. Kaiser et al. (1998) has also repeated some of Holme’s anchor dredge stations on the Looe-Eddystone scallop ground using a replica of the original dredge.
It is unwise to undertake multivariate analysis on samples containing fewer than 30 individuals. In such circumstances random effects have an undue influence on resulting ordination. Many of Holme’s samples fall below the threshold of 30 individuals and if they are excluded only 181 samples remain. In such an analysis the most practical approach would be to analyse molluscs and echinoderms together while excluding all other taxa. In this case, a useful quantitative analysis would be possible. The analysis would refine assemblages defined by Holme and would facilitate detection of change.
3.5 Datasets – Brittle-star Survey
3.5.1 Description
These surveys took place between 1965 and 1983 (mostly between 1970 and 1974). They were undertaken to map and explain distribution of beds of the brittle-star Ophiothrix fragilis, a species that has been highly variable in abundance and distribution since first reported in the Channel by Allen in the 1890s.
Although notebooks in the Holme Archive are entitled “Brittle-star Survey” they contain fully quantitative (mostly) records of all echinoderms taken from 329 stations (mostly) along the English side of the English Channel. Some of these stations were repeats of English Channel survey stations. However, data are not directly comparable as sampling was undertaken using a “mini-Aggasiz” trawl. This one-metre-wide beam trawl will sample surface living fauna more efficiently and infauna less efficiently than an anchor dredge.
14 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
3.5.2 Potential for resurvey and analysis
The brittle-star bed survey provides a very valuable data set and although some species information from it has been entered into the MBA database, full extraction to a modern database is vital if use is to be made of the datasets. As with anchor dredge data, it is unlikely that any novel pattern of community distribution would emerge from a multivariate re-analysis of the brittle-star data set. It is, however, expected that more subtle variability within easily-identified assemblages would become apparent. This might increase the ease with which temporal changes would be detected.
3.6 Datasets - Death Assemblages
3.6.1 Description
When analysing material retained in anchor dredge samples, Holme made thorough records of all dead shell material. On the majority of occasions the species list that he records is far longer than that for living material. For more common species spatial variability in the number of live animals is well correlated with number of empty shells.
3.6.2 Potential for resurvey and analysis
The degree to which the death assemblage can be exploited in modern ecological studies is highly dependent on age of shells that are sampled and degree to which they have been transported. If shells are relatively recent and there is little transport, then it is possible that the death assemblage might give a better estimate of local molluscan biodiversity than would be arrived at by small-scale sampling of live animals.
3.7 Videotape, videocassettes and photographic transparencies archive
3.7.1 Description
Archive holdings: Archives hold 106 videotapes (reel to reel Sony HD format) and 59 video cassettes (including 15 from the Irish Sea) in VHS format, 90 rolls of 35 mm colour transparency film stored in the National Marine Biological Library either in a storage cabinet or in original film canisters. There are also 21 tapes from a 1971 BBC expedition to the Comoros Islands and 4 videotapes from dives made in the English Channel in 1971 in the submersible Pisces. In the notes that follow only the material relating to the English Channel will be discussed.
Methods used by Holme: Equipment that Holme used in his video surveys changed as technology evolved. Initial television surveys (Holme & Barrett 1977) mounted a video and a still camera on top of a sled at 60cm above the sea floor. The television camera pointed forwards at an angle of 45° while the still camera pointed vertically downwards. The TV image covered had a central field width of 45.6cm and, as with any other forward pointing image, covered an area trapezoid in shape. The still camera gave an image of an area 56.7cm x 38cm. Later the angle of the TV camera was changed to either 26° from the vertical or 35° from the vertical giving a smaller frame size and better resolution of small animals. The protocol for the collection of still images was also variable. Initially a photograph was taken as a response to sighting of an interesting target on real-time video display. Later, photographs were taken every 20-30 seconds.
Videotapes: Videotapes are from the period 1976 to 1980 and were recorded at stations from Cornwall to the Isle of Wight. Eight tapes are from the Breton coast of France. It has not been possible to review these reel-to-reel tapes, as the MBA no longer hold a machine capable of playing old-format video. Contact has been made with staff at BBC Bristol who are confident that it will be possible to find a company to do transcription at commercial rates. A small number of video records from 1976 have been transcribed onto videocassette. As each of these cassettes is marked as containing the contents of four separate tape reels, it is assumed that the VHS tapes represent edited highlights. The VHS tapes inspected are in black and white and consequently it is assumed the same is true for the entire collection of reel-to-reel tapes. The analysis of seafloor videos recorded in Holme’s notebooks contains little detail of fauna but give useful information on benthic habitats. Positions of video tows are geographically referenced.
15 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
a b
Figure 9 - Holme benthos video sleds a) 1977, b)1984.
Videocassettes: The majority of videocassettes were recorded in the years 1982 and 1984. They are in colour and those that have been reviewed are playable on a modern VHS video-recorder. Quality is generally poor in comparison to modern under-water video, and relates largely to height of camera above sediment, uneven lighting and, often, jerky movement of the sledge. While image discrimination is adequate for large bodied animals such as scallops, smaller species are often difficult to identify. Identification will be improved when the video- and still images are viewed together.
Photographic transparencies: Transparencies that have been examined are of high quality and are more than sufficient to make useful identifications of visible animals larger than 5mm across. Further information can be gleaned from examination of bioturbational features, e.g. mounds created at burrow entrances.
A b
C d
Figure 10: Examples of photographic transparencies a) 25/05/77 Gerran Bay; b) 14/05/82 South of Portland; c) 19/06/74 Eddystone; d) 18/06/75 Plymouth
16 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
3.7.2 Potential for resurvey and analysis
Video images: Twenty percent of videocassettes have been viewed in the Image Analysis Laboratory of the University of Plymouth and have been manipulated electronically to improve the image quality. In most cases, contrast and brilliance can be adjusted to compensate for poor lighting and this usually improves species discrimination. Although there were changes in image size recorded, this does not preclude comparison of abundance of features in images. Modern software packages can be used to project virtual quadrats (perspective or ‘Canadian’ grids) of the size of the smaller images onto those that of are of a greater area. Direct comparisons of area can thus be made. A second difficulty to be overcome is that images of smaller areas will have better resolution of small features than will bigger images. Calculations can be made of the smallest feature resolved in a large image and feature smaller than this can be discounted when a small image is analysed. The sampling strategy employed analysed strips of sea floor equivalent to 5m2.
It is unlikely that image enhancement will reveal much detail missed in the original analysis but it would facilitate comparison with any new images that might be collected if any of the Holme sites were to be revisited.
Photographic transparencies: There is some potential for re-analysis, particularly in areas where biological features are abundant. There is a great need for data on spatial structure of marine benthic assemblages, particularly with regard to megafaunal species. While some images have sufficient features to make such studies possible, in most cases mean density of organisms is low. Information on abundance of megafauna species is better taken from high quality video images.
Potential for display of information from surveys: Information, including images, collected during surveys by Norman Holme represent the best descriptive coverage of seabed types including fauna that is available at present. Images provide a particularly useful form of information. Use has been made of similar material to that collected by Holme in the Irish Sea Seabed Image Archive (ISSIA) (see demonstration at www.marlin.ac.uk/conference99) and a similar exercise including other sources of images but disseminated on the Internet would be a significant resource for research and education.
3.8. Summary and context of results
3.8.1 Overview
Holme undertook a comprehensive mapping exercise of molluscs and echinoderms of the English Channel, providing a baseline against which change can be assessed. Many of his data already reside in the MBA database and, from this database, comprehensive synoptic maps of faunal distributions can be generated (Annex 4). These maps alone can be used to provide a basis for assessing change. However, Holme examined biogeography of individual species and noted spatial and temporal trends in their distribution. Main groupings are as follows:
Group 1 - General distribution: Widely distributed and often preferring areas of substantial water movement e.g. Ophiothrix fragilis, Chlamys opercularis, Glycimeris glycimeris, Natica alderi and Echinocardium cordatum. In addition there is a suite of species that are restricted to soft sediments that occur off England but not France. Similarly, there are species found only on the French side.
Group 2 - Western distribution: Species that extend as far as Plymouth and Start Point on the northern shore to Guernsey on the south. Some may extend further in deep water. e.g. Arca tetragona, Chlamys tigerina, Astarte sulcata, Gari costulata, Hyalinoecia tubicola and Ophiocomina nigra.
Group 3 - West Channel. Species that extend as far up-Channel as Weymouth Bay and the tip of the Cotentin Peninsula. The limits to their distribution may relate more to the distribution of sandy substrata than to other factors. e.g. Cyprina islandica, Dosinia lupinus, Chamelea gallina, Callianassa subterranea, Upogebia stellata, Amphiura filiformis and Lapidoplax digitata.
Group 4 - Cornubian. Warm water species with limited penetration of the Channel. Most occur in shallow water e.g. Tellina squalida, Sipunculus nudus and Marthasterias glacialis.
Group 5 - Sarnian. Distribution centred around the Channel Islands but extending, in some cases to Portland and the Isle of Wight or even into Cornish estuaries. e.g. Nucula nucleus, Chlamys varia, Venus verrucosa, Venerupis rhomboides, Calyptraea chinensis and Gari depressa.
Group 6 - Eastern. Cold water forms commonest in the eastern parts of the Channel e.g. Spisula eliptica, Buccinum undatum and Mya truncata.
17 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
3.8.2 Detecting fishery-induced change Benthic habitats differ in their susceptibility to disturbance by trawling. The impact of disturbance from commercial trawlers is different for each habitat, with benthos within stable mud, gravel and biogenic habitats (i.e. maerl) having least resilience, less consolidated coarser sediments are typically less heavily impacted and quicker to recover (Collie et al. 2000). Theoretically, fishing disturbance should be lower in habitats with more natural disturbance, perhaps from strong currents or tides (Jennings & Kaiser 1998). Responses among species will vary depending upon their physical and behavioral attributes. In each case, these should be considered when examining long-term change. Should re-survey go ahead, change would be expected to be greater in the least resilient species within the most vulnerable habitats.
3.8.3 Detecting climate-induced change The Holme archive offers the opportunity to make a simple comparison of mollusc and echinoderm assemblages and their distribution in the period 1950-1985 with those that presently exist. If benthos of the Channel were to be re-surveyed some change is to be expected, as benthic assemblages are seldom static. The question is how much of the any observed change could be linked to a change in climate? The broad spatial surveys that Holme carried out identified groups of species with characteristic patterns of distribution that can be linked to the temperature regime of areas that they inhabit. This information can direct interpretation of change. It is also anticipated that re-analysis of Holme’s original data will provide temperature regime indicative groupings of species that will further aid interpretation. Lastly, there are also a small number of sites at which sampling has been repeated throughout the past century. These give a background to dynamics of change in benthos and would further support its explanation.
If climate change has affected benthic assemblages these patterns of distribution could be used to predict changes in distribution of various species groups between the time of Holme’s surveys and the present day. The following predictions of response to warming can be made:
· Western species would retreat to the west or into deep water. · Western Channel Species are unlikely to change · Cornubian species would spread up-Channel · Sarnian species would increase distribution away from Channel Islands · Eastern Species would retreat up-Channel.
Offshore data collected by Holme should be viewed together with that collected by dredge sampling for hard substratum species in the English Channel by Cabioch et al. (1977).
3.8.4 Conclusions and recommendations
Detecting changes in English Channel seafloor habitats and communities. Unlike fish, most large benthic animals have limited mobility. The majority of individuals will move only a matter of metres during their life. When seafloor conditions change adversely most benthic animals do not have the option to swim away, they must either survive or die. Those that survive will often suffer some reduction in their reproductive performance and/or growth. When conditions on the seafloor change, such change is usually reflected in composition of benthic fauna.
Holme’s original surveys were essentially qualitative and two main benthic sampling series used different methodologies. In addition, many areas have either video or photographic records of the sea floor. If a re-survey were to take place, comparable sampling would be essential. Ideally, both anchor dredge and mini-Aggasiz trawl would be used in any new survey as both sample different elements of fauna. The dredge will collect a better sample of infaunal molluscs while the trawl will sample epibenthic echinoderms more efficiently. If a choice between the two methods were necessary, greater species-richness of molluscs would argue in favour of using the dredge.
Imaging methods would best to quantify epifaunal species, however the choice of method is difficult. Good spatial coverage could be provided (at relatively low cost) by using a bed-hop still camera taking still photographs but as image size would be small, mean number of individuals in each image would usually be low. As a consequence of high variance, detecting future changes would be difficult. Towed sled video, as used by Holme would be an option worth considering, provided it could be deployed slowly and smoothly. Towed sleds provide an image in the form of a continuous transect, but this can be broken down into fixed lengths that approximate to quadrats. Many of the disadvantages of towed video would be overcome by use of a small ROV. These vehicles can be flown at a speed controlled by an operator on deck and camera pan tilt and zoom can be controlled to aid animal identification. ROVs are expensive and perhaps the best value for money in a new survey of the Channel benthos would come from a drop-down digital video camera fitted with a laser scaling system. This would provide scaled images with less resolution than a still camera but could be used from a drifting ship to provide transect data.
A re-survey of the whole area investigated by Holme would be a costly undertaking and cheaper alternatives might be considered. The most crucial areas to re-survey would be those either side of well documented breaks in distribution patterns. In particular, sampling 18 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
in the Plymouth/Start Point area and Weymouth Bay/Isle of Wight should indicate community change. The former area also has the advantage of containing the Looe and Rame-Eddystone grounds, both of which have long histories of benthic recording. This smaller scale- surveys should be supported by transects into mid-Channel as Western Channel species might retreat to greater depth.
Use of Photographic & Video Archive. The archive of good-quality, geographically referenced transparencies is a valuable resource for anybody wishing to have information on seafloor characteristics more detailed than those provided on navigation charts. Such information is seldom available elsewhere. Precise positions for each image are unavailable, as although the start and end co-ordinates of most tows can be determined from Holme’s notebooks, the exact track steered was not necessarily a straight line. Holme refers to the position of many of his images/and videos to an ICES box and this might well be the most appropriate way to deal with them. In many of the areas photographed, the images on a single tow show a reasonably homogeneous sea floor and it may be reasonable to extrapolate these conditions to a greater area that can actually be sampled. However, in areas where there is strong tidal scour, the bottom environment can be highly patchy and as Holme noted, ‘no two tows can be regarded as replicates’. The video archive is best used in support of transparencies.
4 Final conclusions and recommendations
Comprehensive community-level archived datasets are invaluable for examining long-term changes in demersal fish and benthic invertebrate communities, but are rare, particularly timescales of more than 50 years. Historic studies have concentrated upon commercially valuable species, the conservation status of non-target fishes and invertebrates have often been overlooked, exceptionally to the extent that some taxa are commercially extinct. Overall, the benthos datasets identify taxa with less precision, but thorough records are available for echinoderms and molluscs. With modern statistical techniques these data can now be analysed more effectively than ever thought possible. The MBA demersal fish and invertebrate datasets represent excellent baselines for comparisons with modern resurveys and testing the ecosystem effects of fishing.
In order to use these historic data sets to their full capacity, we recommend the following steps.
To investigate effects of fishing:
· Identification and assessment of indices of status of demersal fish and benthic invertebrate assemblages · Continuation of demersal fish resurveys initiated during the project and analyses of patterns in existing data · Resurvey Holme benthos sites, to determine the species vulnerable to disturbance and their life-history characteristics
To investigate effects of climate change:
· Determination of appropriate spatial-scales that might be used to detect faunal changes that result from climatic or hydrographic events. · From historic data and contemporary resurvey, develop quantitative indices of climate-induced changes in fauna to incorporate into predictive models of future faunal distribution using UKCIP climate change scenarios.
5 References
Allen, E.J. (1899) On the fauna and bottom deposits near the thirty fathom line from the Eddystone grounds to Start Point. Journal of the Marine Biological Association of the U.K., 5, 365-542 Botsford, L.W. & Castilla, J.C. & Perterson, C.H. (1997) The management of fisheries and marine ecosystems. Science, 277, 509-515. Cabioch, L., Gentil, F., Glaçon, R., & Retière, C. (1977) Le macrobenthos des fonds meubles de la Manche: distribution générale et écologie. In: Biology of Benthic Organisms. 11th European Symposium on Marine Biology, Galway, October 1976, ed. by B.F. Keegan, P. O'Ceidigh & P.J.S. Boaden, 115-128. Oxford, Pergamon Press. Clarke, K.R. & Warwick, R.M. (1994) Change in marine communities: an approach to statistical analysis and interpretation. Plymouth Marine Laboratory, Plymouth, UK. Collie, J.S., Hall, S.J., Kaiser, M.J. & Poiner, I.R. (2000) A quantitative analysis of fishing impacts on shelf-sea benthos. Journal of Animal Ecology, 69, 785-798. Cook, R.M., Sinclair, A. & Stefansson, G. (1997) Potential collapse of North Sea cod stocks. Nature, 285, 521-522. Davis, A.J., Jenkinson, L.S., Lawton, J.H., Shorrocks, B. & Wood, S. (1998) Making mistakes when predicting shifts in species range in response to global warming. Nature, 391, 783-786. Dulvy, N.K., Metcalfe, J.D., Glanville, J., Pawson, M.G. and Reynolds, J.D. (2000) Fishery stability, local extinctions, and shifts in community structure in skates. Conservation Biology, 14, 283-293. Froese, R. & Pauly, D. (1999) Fishbase (online) (eds.) cited 31 May 2001. (http://www.fishbase.org) Gomes, M.C., Haedrich, R.L. & Villagarcia, M.G. (1995) Spatial and temporal changes in the groundfish assemblages on the northeast newfoundland Labrador shelf, north-west Atlantic 1978-1991. Fisheries and Oceanography 4, 85-101. Greenstreet, S.P.R. & Hall, S.J., (1996) Fishing and the ground-fish assemblage structure in the north-western North Sea: an analysis
19 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
of long term and spatial trends. Journal of Animal Ecology, 65, 577-598. Hall, S.J. (1998) The Effects of Fishing on Marine Ecosystems and Communities. Blackwell Science. Oxford. UK Holme, N.A. (1961) The bottom fauna of the English Channel. Journal of the Marine Biological Association of the U.K., 41, 397-461. Holme, N.A. (1966) The bottom fauna of the English Channel. II. Journal of the Marine Biological Association of the U.K., 46, 401- 493. Holme, N.A. & Barrett, R.L.A. (1977) A sledge with television and photographic cameras for quantitative investigation of epifaunal on the continental shelf. Journal of Marine Biological Association of the U.K., 57, 391-404. Holme, N.A., & Wilson, J.B. (1985) Faunas associated with longitudinal furrows and sand ribbons in a tide-swept area in the English Channel. Journal of the Marine Biological Association of the U.K., 65: 1051-1072. Hutchings, J.A. (2000) Collapse and recovery of marine fishes. Nature, 406, 882-885. Hyndes, G.A., Platell, M.E., Potter, I.C. & Lenanton, R.C.J. (1999). Does the composition of the demersal fish assemblages in temperate coastal waters change with depth and undergo consistent seasonal changes? Marine Biology, 134, 335-352. Jennings, S., Reynolds, J.D. & Mills, S.C. (1998) Life history correlates of responses to fisheries exploitation. Proceedings of the Royal Society of London B, 265, 333-339. Jennings, S., Dinmore, T.A., Duplisea, D.E., Warr, K.J. & Lancaster, J.E. (2001) Trawling disturbance can modify benthic production processes. Journal of Animal Ecology, 70, 459-475. Jennings, S., Greenstreet, S.P.R. & Reynolds, J.D. (1999) Structural change in an exploited fish community: a consequence of differential fishing efforts on species with contrasting life-histories. Journal of Animal Ecology, 68, 617-627. Jennings, S. & Kaiser, M.J. (1998) The effects of fishing on marine ecosystems. Advances in Marine Biology 34: 201-352. Kaiser, M.J., Edwards, D.B., Armstrong, P.J., Radford, K., Lough, N.E.L., Flatt, R.P. & Jones, H.D. (1998) Changes in megafaunal benthic communities in different habitats after trawling disturbance. ICES Journal of Marine Science, 55, 353-361. Kaiser, M.J., Ramsay, K., Richardson, C.A., Spence, F.E. & Brand, A.R. (2000) Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology, 69, 494-503. Maddock, L. & Swann, C.L. (1977). A statistical analysis of some trends in sea temperature and climate in the Plymouth area in the last 70 years. Journal of the Marine Biological Association of the U.K., 57, 317-338. Marine Biological Association (1957). Plymouth Marine Fauna 3rd Edition. Marine Biological Association of the UK, Plymouth, U.K. Murawski, S.A. (1993) Climate change and marine fish distributions: forecasting from historical analogy. Transactions of the American Fisheries Society, 122, 647-658. O’Brien, C.M., Fox, C.J., Planque, B. & Casey, J. (2000) Climate variability and North Sea cod. Nature, 404, 142 Pauly, D., Christensen, V., Dalsgaard, J., Froese, R. and Torres, F.C. (1998) Fishing down marine food webs. Science, 279, 860-863. Pauly, D., Palomares, M.A., Froese, R. Sa-a, P., Vakily, M., Preikshot, D. & Wallace, S. (2001) Fishing down Canadian aquatic food webs. Canadian Journal of Fisheries and Aquatic Sciences, 58, 51-62. Rice, J. & Gislason, H. (1996) Pattern of change in the size spectra of numbers and diversity of the North Sea fish assemblage, as reflected in surveys and models. ICES Journal of Marine Science, 53, 1214-1225. Rijnsdorp, A.D., Vethaak, A.D. and van Leeuwen, P.I. (1992) Population biology of dab Limanda limanda in the southeastern North Sea. Marine Biology Progress Series, 91, 19-35. Rijnsdorp, A.D., Buys, A.M., Storbeck, F. & Visser, E.G. (1998) Microscale distribution of beam trawl effort in the southern North Sea between 1993 and 1996 in relation to the trawling frequency of the sea bed and the impact on benthic organisms. ICES Journal of Marine Science, 55, 403-419. Rogers, S.I., Clarke, K.R. & Reynolds, J.D. (1999) The taxonomic distinctness of coastal bottom-dwelling fish communities of the North-east Atlantic. Journal of Animal Ecology, 68, 769-782. Rogers, S.I. & Ellis, J.R. (2000) Changes in the demersal fish assemblages of British coastal waters during the 20th century. ICES Journal of Marine Science, 57, 866-881. Schneider, S.H. (2001) What is ‘dangerous’ climate change?’ Nature 411, 17-19. Southward, A.J. (1980) The Western English Channel – an inconsistent ecosystem? Nature, 285, 361-366 Southward, A.J. & Boalch, G.T. (1993) The Marine Resources of Devon's coastal waters In: M. Duffy, S. Fisher, B. Greenhill, D.J. Starkey & J. Youings (eds). The New Maritime History of Devon., Vol. 1, 61-71. London: Conway Maritime Press. Southward, A.J. & Butler, E.I. (1972) Fluctuations in the temperature of the sea off Plymouth from 1921 to 1971. Journal of the Marine Biological Association of the U.K., 52: 931-937. Southward, A.J., Hawkins, S.J. & Burrows, M.T. (1995) Seventy years of observations of changes in distribution and abundance of zooplankton and intertidal organisms in the Western English Channel in relation to rising sea temperature. Journal of Thermal Biology, 20, 127-155. Walker, P.A. & Heessen, H.J.L. (1996) Long term changes in the ray populations in the North Sea. ICES Journal of Marine Science, 53, 1085-1093.
20 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 1
Vessels employed on MBA demersal fish surveys 1913-2001
Vessel SS Oithona RV Salpa RV Sabella RV Sula RV Sarsia RV Squilla
Years engaged in standard hauling 1913-1920 1921-1922 1950-1952 1952-1973 1979 1974-2001 Vessel length (m) 25.3 26.8 27.4 18.8 39.0 18.3 Power Steam Steam Motor Motor Motor Motor Number of hauls 136 68 143 173 19 148 Mean tow duration (mins) 44 59 50 60 55 57 Tow speed (knots - estimated) 2.5 - - - - 2.5 Headline length (m) 19.5 - - 16.2 18.9 19.8 Groundrope length (m) 27.4 - - 25.6 27.4 19.8 Approximate stretched mesh (mm) - - - 90 100 75-90 Cod-end stretched mesh (mm) 25-38 - - 69.9 63.5 70-75 Reference Kyle (1903) - - Holme (1974) Holme (1974) -
SS RV Oithona Sula
RV Salpa RV Sarsia
RV RV Sabella Squilla
21 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 2:
Number of demersal fish hauls off Plymouth 1913-1986. During 2001 twenty two hauls have been carried between Jan-April.
Research Vessel Year RV Oithona RV Salpa RV Sabella RV Sula RV Sarsia RV Squilla Total 1913 70 70 1914 6 6 1919 27 27 1920 33 33 1921 53 53 1922 15 15 1950 45 45 1951 40 40 1952 58 6 64 1953 29 29 1954 21 21 1955 22 22 1956 29 29 1957 33 33 1958 3 3 1967 4 4 1968 9 9 1969 5 5 1970 3 3 1971 4 4 1972 4 4 1973 1 1 1974 6 6 1975 5 5 1976 9 9 1977 17 17 1978 30 30 1979 19 21 40 1983 17 17 1984 7 7 1985 26 26 1986 10 10 Total 136 68 143 173 19 148 687
22 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 3
Mean duration of historic demersal fish hauls off Plymouth 1913-1986.
Research Vessel Year RV Oithona RV Salpa RV Sabella RV Sula RV Sarsia RV Squilla Mean
1913 46.1 46.1 1914 73.5 73.5 1919 38.3 38.3 1920 38.3 38.3 1921 58.1 58.1 1922 64 64 1950 48.7 48.7 1951 54.7 54.7 1952 46.7 47.5 46.8 1953 60 60 1954 60 60 1955 60 60 1956 60 60 1957 60 60 1958 60 60 1967 60 60 1968 60 60 1969 60 60 1970 60 60 1971 60 60 1972 60 60 1973 60 60 1974 60 60 1975 60 60 1976 60 60 1977 58.2 58.2 1978 56 56 1979 55.3 48.6 51.8 1983 60 60 1984 60 60 1985 58.5 58.5 1986 60 60
Mean 43.8 59.4 49.6 59.6 55.3 57.1 53.7
23 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 4
Number of demersal fish hauls off Plymouth during each month 1913-1986
Year Month Total J F M A M J J A S O N D
1913 13 26 11 16 4 70 1914 2 2 2 6 1919 11 12 4 27 1920 13 20 33 1921 5 9 9 18 5 7 53 1922 7 3 4 1 15 1950 2 1 4 1 8 5 13 7 4 45 1951 1 2 4 2 10 2 4 9 2 4 40 1952 4 19 16 15 6 3 1 64 1953 1 2 4 4 3 3 2 2 1 2 2 3 29 1954 4 3 3 3 1 2 1 4 21 1955 1 3 2 1 2 1 1 3 4 3 1 22 1956 3 2 4 4 3 3 1 3 4 2 29 1957 2 2 4 3 2 3 4 2 2 5 3 1 33 1958 3 3 1967 1 1 2 4 1968 1 1 2 1 1 1 1 1 9 1969 1 1 1 1 1 5 1970 1 1 1 3 1971 1 1 2 4 1972 1 1 1 1 4 1973 1 1 1974 1 1 3 1 6 1975 1 1 1 1 1 5 1976 6 2 1 9 1977 2 4 2 3 2 4 17 1978 4 2 2 1 5 1 6 2 7 30 1979 1 1 11 17 10 40 1983 2 1 1 4 8 1 17 1984 2 1 2 2 7 1985 3 2 4 12 5 26 1986 2 2 4 2 10
Total 36 28 37 21 37 41 144 77 114 81 37 34 687
24 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 5: Details and characteristics of species in demersal fish hauls 1913-2001
Demersal species groupings. Distribution, life-history and trophic level information taken from key facts in FishBase (Froese & Pauly 2001). C: Species with commercial value to Plymouth inshore demersal fishers, NC: no (or little) commercial value.
Southern limit Median Commercial Northern Northern Distribution N. Distribution L. max L. mat Trophic Taxa Common name Value limit °N Hemisphere Hemisphere Category (cm) (cm) level °N °N
Galeorhinus galeus Tope C 68 0.0 34.0 Southern 175.0 104.3 4.2 Scyliorhinus stellaris nurse-hound NC 64 12.0 38.0 Southern 170.0 85.6 4.0 Scyliorhinus canicula lesser-spotted dogfish NC 63 12.0 37.5 Southern 100.0 53.5 3.6 Mustelus mustelus Smooth-hound NC 58 0.0 29.0 Southern 200.0 98.8 3.8 Mustelus asterias starry smooth-hound NC 60 34.0 47.0 Ch-Biscay 140.0 72.1 3.7 Raja spp. skates and rays C 63.3* 6.9* 35.1* Southern 93.0* 47.9* 3.7* Squalus acanthias spurdog C 72 0.0 36.0 Southern 160.0 65.6 4.3 Squatina squatina angel shark NC 65 26.0 45.5 Ch-Biscay 183.0 91.4 4.0 Torpedo spp. **** electric rays NC 59 0.0 29.5 Southern 180.0 90.0 4.5 Conger conger conger eel C 66 0.0 33.0 Southern 300.0 109.9 4.3 Gadus morhua cod C 78 35.0 56.5 Northern 200.0 97.3 3.7 Melanogrammus aeglefinus haddock C 78 34.0 56.0 Northern 100.0 41.7 3.6 Merlangius merlangus whiting C 72 35.0 53.5 Northern 70.0 27.6 4.3 Micromesistius poutassou blue whiting NC 79 26.0 52.5 Northern 50.0 25.2 4.0 Pollachius pollachius pollack C 72 44.0 58.0 Northern 130.0 67.5 4.5 Pollachius virens saithe C 77 34.0 55.5 Northern 130.0 55.0 3.7 Raniceps raninus tadpole fish NC 68 44.0 66.0 Northern 27.5 28.9 3.8 Trisopterus luscus bib NC 62 25.0 43.5 Ch-Biscay 46.0 23.5 3.7 Trisopterus minutus poor cod NC 66 28.0 47.0 Ch-Biscay 40.0 19.6 3.6 Enchelyopus cimbrius four-bearded rockling NC 64 20.0 42.0 Southern 41.0 24.5 3.1 Gaidropsarus mediterraneus shore rockling NC 58 36.0 47.0 Ch-Biscay 50.0 29.0 3.4 Gaidropsarus vulgaris three-bearded rockling NC 74 36.0 55.0 Northern 40.0 23.8 3.6 Molva molva common ling C 80 20.0 50.0 Northern 200.0 89.9 4.2 Merluccius merluccius hake C 70 15.0 42.5 Southern 140.0 57.8 4.5 Phycis blennoides greater fork-beard NC 69 30.0 49.5 Ch-Biscay 110.0 58.3 3.4 Syngnathus acus greater pipefish NC 71 0.0 35.5 Southern 46.0 27.0 3.2 Lophius spp. anglerfishes C 63.5* 32.0* 47.8* Ch-Biscay 150* 63.9* 4.5* Blennius ocellaris butterfly blenny NC 50 20.0 35.0 Southern 20.0 12.9 3.5 Lipophrys pholis shanny NC 60 30.0 45.0 Ch-Biscay 30.0 18.5 3.0 Callionymus reticulatus reticulated dragonet NC 66 35.0 50.5 Northern 11.0 7.6 3.3 Callionymus maculatus dragonet NC 64 14.0 39.0 Southern 16.0 10.6 3.3*** Callionymus lyra dragonet NC 70 15.0 42.5 Southern 30.0 15.0 3.3 Gobiidae gobies NC 64.2* 28.6* 46.4* Ch-Biscay 8.5* 6* 3.2* Cepola macrophthalma red bandfish NC 61 10.0 35.5 Southern 80.0 36.7 3.2 Diplecogaster bimaculata two-spotted clingfish NC 71 36.0 53.5 Northern 4.0 3.1 3.4 Lepadogaster lepadogaster cornish sucker NC 61 14.0 37.5 Southern 7.5 5.4 3.4*** Ctenolabrus rupestris goldsinny NC 71 28.0 49.5 Ch-Biscay 18.0 10.1 3.5 Labrus mixtus cuckoo wrasse NC 71 14.0 42.5 Southern 40.0 19.9 3.9 Labrus bergylta ballan wrasse NC 70 28.0 49.0 Ch-Biscay 60.0 31.9 3.4 Dicentrachus labrax sea bass C 66 13.0 39.5 Southern 100.0 44.4 3.8 Mullus surmuletus red mullet C 55 14.0 34.5 Southern 40.0 16.9 3.3 Serranus cabrilla comber NC 57 0.0 28.5 Southern 40.0 23.8 4.3 Pagellus spp. red sea-bream C 65 20.0 42.5 Southern 70.0 31.2 3.7 Spondyliosoma cantharus black sea-bream C 68 0.0 34.0 Southern 60.0 29.0 3.3 Chirolophis ascanii Yarrel's blenny NC 66 50.0 58.0 Northern 25.0 15.7 3.0 Echiichthys vipera lesser weever NC 60 28.0 44.0 Ch-Biscay 15.0 10.0 4.4 Trachinus draco greater weever NC 66 27.0 46.5 Ch-Biscay 45.0 26.5 3.5
25 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Southern limit Median Commercial Northern Northern Distribution N. Distribution Trophic Taxa Common name L. max L. mat Value limit °N Hemisphere Hemisphere Category level °N °N
Arnoglossus spp. scaldfishes NC 59.7 19.0* 39.4* Southern 21.0* 13.5* 3.7* Glyptocephalus cynoglossus witch C 74 36.0 55.0 Northern 60.0 24.8 3.1 Hippoglossus hippoglossus halibut C 74 37.0 55.5 Northern 240.0 91.6 4.6 Limanda limanda dab C 66 42.0 54.0 Northern 40.0 19.3 2.8 Microstomus kitt lemon sole C 70 40.0 55.0 Northern 65.0 36.6 3.2 Platichthys flesus flounder NC 60 30.0 45.0 Ch-Biscay 58.0 22.5 3.5 Pleuronectes platessa plaice C 70 20.0 45.0 Ch-Biscay 100.0 43.5 3.1 Lepidorhombus whiffiagonis megrim NC 70 26.0 48.0 Ch-Biscay 60.0 32.7 4.1 Phrynorhombus spp. Eckstrom's & Norway topknot NC 65.8* 33.7* 49.0* Ch-Biscay 16.0* 10.6* 4.0* Scophthalmus maximus turbot C 70 30.0 50.0 Northern 100.0 37.9 3.7 Scophthalmus rhombus brill C 64 30.0 47.0 Ch-Biscay 75.0 41.5 3.8 Zeugopterus punctatus topknot NC 64 44.0 54.0 Northern 25.0 15.7 4.0 Buglossidium luteum solenette NC 66 35.0 50.5 Northern 15.0 10.0 3.4 Microchirus variegatus thickback sole NC 60 15.0 37.5 Southern 20.0 12.9 3.3 Solea solea dover sole C 65 10.0 37.5 Southern 70.0 29.9 3.3 Agonus cataphractus pogge NC 66 49.0 57.5 Northern 21.0 9.5 3.4 Cyclopterus lumpus lumpsucker NC 80 50.0** 65.0 Northern 60.0 30.5 3.7 Chelidonichthys gurnardus grey gurnard C 70 20.0 45.0 Ch-Biscay 60.0 26.0 3.6 Chelidonichthys lastoviza streaked gurnard C 71 0.0 35.5 Southern 40.0 21.3 3.5 Chelidonichthys cuculus red gurnard C 60 15.0 37.5 Southern 50.0 23.8 3.8 Chelidonichthys lucerna tub gurnard C 66 9.0 37.5 Southern 75.0 38.5 3.9 Capros aper boarfish NC 60 10.0 35.0 Southern 30.0 18.5 3.2 Zeus faber john dory C 63 0.0 31.5 Southern 90.0 37.6 4.5
C – species of commercial value (as both target and non-target), NC – species of no commercial value (except as forage). Northern – Median distribution higher than 50°N Ch-Biscay – Median distribution in between English-Channel and Bay of Biscay Southern – Median distribution lower than 43°N * Mean value of known species belonging to taxonomic group within Plymouth waters ** Occurrence in Plymouth farther south than fishbase records *** Taken from data for similar sized, closely related species **** Data taken from Torpedo nobiliana
Species grouped for analyses
Species groupings Species Common name
Lophius spp. L. budegassa anglerfish L. piscatorius black-bellied angler Gobiidae Buenia jeffreysii Jeffrey’s goby Crystallogobius linearis crystal goby Gobius niger black goby Pomatoschistus pictus painted goby P. minutes sand goby Pagellus spp. P. bogaraveo red sea bream P. erythrinus pandora Arnoglossus spp. A. laterna scaldfish A. thori Thor’s scaldfish A. imperalis imperial scaldfish Phyrnorhombus spp. P. regius Eckstrom’s topknot P. norvegicus Norwegian topknot Raja / Leucoraja spp. R. undulata, undulate ray R. montagui spotted ray R. clavata thornback ray R. microocellata small-eyed ray R. brachyura blonde ray L. fullonica shagreen ray L. naevus. cuckoo ray
26 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Pelagic species excluded from analyses. Catches of these species are sporadic and often large, analyses were restricted t demersal species only to remove potential influence of pelagic species on abundance-based multivariate analyses.
Taxa Common name
Trisopterus esmarkii Norway pout Scomber scombrus Atlantic mackerel Alosa alosa allis shad Alosa fallax twaite shad Clupea harengus herring Sardina pilchardus pilchard Sprattus sprattus sprat Engraulis encrasicolus anchovy Trachurus trachurus horse mackerel Ammodytidae sandeels
Phylogenetic relationships of demersal taxa included in analyses
Class Order Family Genus Species
Carcharinidae Galeorhinus galeus Carcharhiniformes Scyliorhinidae Scyliorhinus stellaris Scyliorhinus canicula Trakidae Mustelus mustelus Mustelus asterias Elasmobranchii Rajiformes Rajidae Raja / Leucoraja spp. Squaliformes Squalidae Squalus acanthias Squatiniformes Squatinidae Squatina squatina Torpediniformes Torpedinidae Torpedo spp. Conger conger Anguilliformes Congridae Gadus morhua Melanogrammus aeglefinus Merlangius merlangus Gadidae Micromesistius poutassou Pollachius pollachius Pollachius virens Raniceps raninus Trisopterus luscus Gadiformes Trisopterus minutus Enchelyopus cimbrius Lotidae Gaidropsarus mediterraneus Gaidropsarus vulgaris Molva molva Merluccidae Merluccius merluccius Phycidae Phycis blennoides Gasterosteiformes Syngnathidae Syngnathus acus Lophiiformes Lophiidae Lophius spp. Blennius ocellaris Blennidae Lipophrys pholis Callionymus reticulatus Callionymiidae Callionymus. maculatus Callionymus lyra Gobiidae Gobiidae Cepolidae Cepola macrophthalma Gobiesocidae Diplecogaster bimaculata Lepadogaster lepadogaster Perciformes Labridae Ctenolabrus rupestris Labrus mixtus Teleostei Labrus bergylta Moronidae Dicentrachus labrax Mullidae Mullus surmuletus Serranidae Serranus cabrilla Sparidae Pagellus spp. Spondyliosoma cantharus Stichaeidae Chirolophis ascanii Trachinidae Echiichthys vipera Trachinus draco Bothidae Arnoglossus spp. Glyptocephalus cynoglossus Hippoglossus hippoglossus Limanda limanda Pleuronectidae Microstomus kitt Platichthys flesus Pleuronectiformes Pleuronectes platessa Lepidorhombus whiffiagonis Phrynorhombus spp. Scopthalmus maximus Scopthalmidae Scopthalmus rhombus Zeugopterus punctatus Buglossidium luteum Solidae Microchirus variegatus Solea solea Agonidae Agonus cataphractus Cyclopteridae Scorpaeniformes Cyclopterus lumpus Chelidonichthys gurnardus Triglidae Chelidonichthys lastoviza Chelidonichthys cuculus Chelidonichthys lucerna Caproidae Zeiformes Capros aper Zeidae Zeus faber
27 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 6 – Fluctuations in annual abundance of species within demersal fish hauls 1913-2001. Log index = Log10mean catch (individuals) per hour
(i) Scyliorhinus stellaris (ii) Scyliorhinus canicula (iii) Galeorhinus galeus
0.6 1.8 0.045
1.6 0.04 0.5 1.4 0.035 0.4 1.2 0.03
1 0.025 0.3 0.8 0.02 Log index Log index Log index 0.2 0.6 0.015 0.4 0.01 0.1 0.2 0.005
0 0 0
(iv) Mustelus mustelus (v) Mustelus asterias (vi) Squalus acanthias 0.07 0.08 1.8 1.6 0.06 0.07 1.4 0.06 0.05 1.2 0.05 0.04 1 0.04 0.8 Log index Log index 0.03 Log index 0.03 0.6 0.02 0.02 0.4 0.01 0.01 0.2
0 0 0
(vii) Conger conger (viii) Syngnathus acus (ix) Micromesistius poutassou
0.25 0.45 0.7 0.4 0.6 0.2 0.35 0.5 0.3 0.15 0.25 0.4
0.2
Log index Log index Log index 0.3 0.1 0.15 0.2 0.05 0.1 0.1 0.05 0 0 0
(x) Merlangus merlangus (xi) Trisopterus luscus (xii) Trisopterus minutus
2.5 1.8 4
1.6 3.5 2 1.4 3 1.2 1.5 2.5 1 2 0.8 Log index Log index Log index 1 1.5 0.6 1 0.5 0.4 0.2 0.5
0 0 0
(xiii) Pollachius pollachius (xiv) Pollachius virens (xv) Gadus morhua 0.4 0.014 0.8
0.35 0.012 0.7
0.3 0.6 0.01 0.25 0.5 0.008 0.2 0.4
Log index Log index 0.006 Log index 0.15 0.3 0.004 0.1 0.2
0.05 0.002 0.1
0 0 0
(xvi) Melanogrammus aeglefinus (xvii) Phycis blennoides (xviii) Merluccius merluccius 0.1 0.14 1.4 0.09 0.12 1.2 0.08 0.07 0.1 1
0.06 0.08 0.8 0.05
Log index Log index 0.06 Log index 0.6 0.04 0.03 0.04 0.4 0.02 0.02 0.2 0.01 0 0 0
1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010
28 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
(xix) Squatina squatina (xx) Molva molva (xxi) Raniceps raninus 0.03 0.4 0.025
0.025 0.35 0.02 0.3 0.02 0.25 0.015 index 0.015 0.2 Log Log index
0.15 Log index 0.01 0.01 0.1 0.005 0.05 0.005
0 0 0
(xxii) Gaidropsarus mediterraneus (xxiii) Gaidropsarus vulgaris (xxiv) Enchelyopus cimbrius
0.08 0.03 0.6
0.07 0.025 0.5 0.06 0.02 0.4 0.05
0.04 0.015 0.3 Log index Log index Log index 0.03 0.01 0.2 0.02 0.005 0.1 0.01
0 0 0
(xxv) Zeus faber (xxvi) Capros aper (xxvii) Dicentrachus labrax 1.6 1.4 0.3
1.4 1.2 0.25 1.2 1 0.2 1 0.8 0.8 0.15 0.6 Log index Log index Log index 0.6 0.1 0.4 0.4 0.05 0.2 0.2
0 0 0
(xxviii) Serranus cabrilla (xxix) Mullus surmuletus (xxx) Pagellus spp.
0.2 1.2 0.45
0.18 0.4 1 0.16 0.35 0.14 0.8 0.3 0.12 0.25 0.1 0.6 0.2 Log index Log index 0.08 Log index 0.4 0.15 0.06 0.1 0.04 0.2 0.02 0.05
0 0 0
(xxxi) Spondyliosoma cantharus (xxxii) Cepola macropthalma (xxxiii) Ctenolabrus rupestris
0.45 1.6 0.16
0.4 1.4 0.14
0.35 1.2 0.12 0.3 1 0.1 0.25 0.8 0.08 0.2 Log index Log index Log index 0.6 0.06 0.15 0.4 0.04 0.1
0.05 0.2 0.02
0 0 0
(xxxiv) Labrus mixtus (xxxv) Labrus bergylta (xxxvi) Echiichthys vipera
0.18 0.3 0.04
0.16 0.035 0.25 0.14 0.03 0.12 0.2 0.025 0.1 0.15 0.02 0.08 Log index Log index Log index 0.015 0.06 0.1 0.01 0.04 0.05 0.02 0.005
0 0 0 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010
29 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
(xxxvii) Trachinus draco (xxxviii) Callionymus reticulatus (xxxix) Callionymus maculatus
0.016 1.8 1.4
0.014 1.6 1.2 1.4 0.012 1 1.2 0.01 1 0.8 0.008 0.8
Log index Log index Log index 0.6 0.006 0.6 0.4 0.004 0.4 0.2 0.002 0.2
0 0 0
(xxxx) Callionymus lyra (xxxxi) Lipophrys pholis (xxxxii) Blennius ocellaris
3 0.06 0.4
0.35 2.5 0.05 0.3 2 0.04 0.25
1.5 0.03 0.2 Log index Log index Log index 0.15 1 0.02 0.1 0.5 0.01 0.05
0 0 0
(xxxxiii) Chirolophis ascanii (xxxiv) Chelidonichthys gurnardus (xxxv) Chelidonichthys lastoviza
0.03 2 1.2
1.8 0.025 1 1.6
1.4 0.02 0.8 1.2
0.015 1 0.6
Log index Log index 0.8 Log index 0.01 0.4 0.6
0.4 0.005 0.2 0.2
0 0 0
(xxxvi) Chelidonichthys cuculus (xxxvii) Chelidonichthys lucerna (xxxviii) Agonus cataphractus
2.5 0.5 0.12
0.45 0.1 2 0.4 0.35 0.08 1.5 0.3
0.25 0.06 Log index Log index 1 Log index 0.2 0.04 0.15
0.5 0.1 0.02 0.05
0 0 0
(xxxix) Cyclopterus lumpus (l) Scopthalmus maximus (li) Scopthalmus rhombus
0.045 0.25 0.4
0.04 0.35 0.2 0.035 0.3 0.03 0.25 0.15 0.025 0.2 0.02 Log index Log index Log index 0.1 0.15 0.015 0.1 0.01 0.05 0.005 0.05
0 0 0
(lii) Zeugopterus punctatus (liii) Lepidorhombus whiffiagonis (liv) Limanda limanda
0.25 0.3 2
1.8 0.25 0.2 1.6
1.4 0.2 0.15 1.2
0.15 1
Log index 0.1 Log index Log index 0.8 0.1 0.6
0.05 0.4 0.05 0.2
0 0 0 2000 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2010
30 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
(lv) Platichthys flesus (lvi) Pleuronectes platessa (lvii) Microstomus kitt 1.2 1.4 1.2
1 1.2 1
1 0.8 0.8 0.8 0.6 0.6
Log index Log index 0.6 Log index 0.4 0.4 0.4
0.2 0.2 0.2
0 0 0
(lviii) Glyptocephalus cynoglossus (lix) Hippoglossus hippoglossus (lx) Solea solea 0.16 0.03 0.6
0.14 0.025 0.5 0.12 0.02 0.4 0.1
0.08 0.015 0.3 Log index Log index Log index 0.06 0.01 0.2 0.04 0.005 0.1 0.02
0 0 0
(lxi) Buglossidium luteum (lxii) Microchirus variegatus (lxiii) Diplecogaster bimaculata
1.2 2 0.08
1.8 0.07 1 1.6 0.06 1.4 0.8 0.05 1.2
0.6 1 0.04 Log index Log index Log index 0.8 0.03 0.4 0.6 0.02 0.4 0.2 0.01 0.2 0 0 0
(lxiv) Lepadogaster lepadogaster (lxv) Rajiidae (lxvi) Arnoglossus spp.
0.016 1.2 2.5
0.014 1 2 0.012 0.8 0.01 1.5
0.008 0.6 Log index Log index Log index 1 0.006 0.4 0.004 0.5 0.2 0.002
0 0 0
(lxvii) Torpedo spp. (lxviii) Lophius spp. (lxix) Phrynorhombus spp.
0.012 1 1.4
0.9 1.2 0.01 0.8
0.7 1 0.008 0.6 0.8 0.006 0.5
Log index Log index Log index 0.6 0.4 0.004 0.3 0.4 0.2 0.002 0.2 0.1
0 0 0 1900 1920 1940 1960 1980 2000 2010 1900 1920 1940 1960 1980 2000 2010 (lxx) Gobiidae
0.6
0.5
0.4
0.3 Log index 0.2
0.1
0 1900 1920 1940 1960 1980 2000 2010
31 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 7 – Temporal abundance and length trends of demersal fish species 1913-2001. Trends (linear regressions) of mean annual abundance and mean length (TL) against year. Regressions on mean length performed if species measurements were taken within five or more sampling years. The intention is to isolate species showing trends, rather than to infer significant relationships, hence no attempts have been made to remove temporal autocorrelation or correct for multiple comparisons have been made.
Abundance Abundance Total Length (cm) (CPUE) (frequency of occurrence) Slope r2 p Slope r2 p Slope r2 p
Galeorhinus galeus 0.000 0.01 0.65 0.000 0.00 0.74 - - - Scyliorhinus stellaris 0.001 0.00 0.88 0.001 0.06 0.23 -0.088 0.00 0.97 Scyliorhinus canicula 0.178 0.22 0.02 0.002 0.05 0.29 1.793 0.46 0.06 Mustelus mustelus 0.000 0.12 0.10 0.000 0.11 0.11 - - - Mustelus asterias 0.000 0.03 0.44 0.000 0.00 0.88 -5.951 0.72 0.07 Squalus acanthias -0.202 0.27 0.01 -0.004 0.38 <0.001 -0.912 0.02 0.79 Raja spp. -0.046 0.16 0.05 -0.004 0.19 0.04 -0.676 0.14 0.16 Squatina squatina 0.000 0.02 0.55 0.000 0.02 0.56 - - - Torpedo spp. 0.000 0.00 0.85 0.000 0.00 0.85 - - - Conger conger -0.001 0.01 0.71 -0.001 0.02 0.52 0.192 0.46 0.06 Gadus morhua 0.022 0.24 0.02 0.003 0.22 0.02 -2.847 0.26 0.05 Melanogrammus aeglefinus 0.000 0.00 0.92 0.000 0.00 0.74 -3.283 0.69 0.08 Merlangius merlangus 0.295 0.07 0.22 0.008 0.64 <0.001 -0.350 0.06 0.27 Micromesistius poutassou 0.014 0.23 0.02 0.005 0.38 <0.001 -3.381 0.53 0.06 Pollachius pollachius 0.003 0.06 0.25 0.001 0.08 0.19 -0.702 0.06 0.40 Pollachius virens 0.000 0.00 0.88 0.000 0.00 0.88 - - - Raniceps raninus 0.000 0.00 0.97 0.000 0.00 0.97 - - - Trisopterus luscus 0.114 0.09 0.17 0.001 0.02 0.53 -0.041 0.00 0.91 Trisopterus minutus 8.439 0.13 0.08 0.007 0.43 <0.001 -0.096 0.01 0.79 Enchelyopus cimbrius 0.006 0.13 0.09 0.001 0.12 0.10 - - - Gaidropsarus mediterraneus 0.000 0.00 0.95 0.000 0.00 0.94 - - - Gaidropsarus vulgaris 0.000 0.03 0.43 0.000 0.03 0.43 - - - Molva molva 0.007 0.23 0.02 0.003 0.25 0.01 -1.243 0.04 0.54 Merluccius merluccius 0.031 0.03 0.45 0.005 0.23 0.02 0.353 0.01 0.67 Phycis blennoides 0.000 0.00 0.98 0.000 0.00 0.99 - - - Syngnathus acus 0.004 0.11 0.12 0.001 0.06 0.25 0.653 0.62 0.01 Lophius spp. 0.028 0.12 0.10 0.002 0.05 0.31 -1.578 0.09 0.20 Blennius ocellaris 0.001 0.00 0.78 0.001 0.01 0.66 -0.208 0.11 0.28 Lipophrys pholis 0.000 0.04 0.34 0.000 0.04 0.34 - - - Callionymus reticulatus 0.082 0.05 0.28 0.001 0.03 0.46 - - - Callionymus maculatus 0.014 0.01 0.68 0.002 0.02 0.47 - - - Callionymus lyra 0.522 0.02 0.48 0.001 0.05 0.27 -0.293 0.15 0.39 Gobiidae 0.000 0.00 0.95 0.001 0.01 0.69 0.192 0.46 0.06 Cepola macrophthalma 0.075 0.20 0.03 0.005 0.29 0.01 0.935 0.04 0.42 Diplecogaster bimaculata 0.000 0.01 0.63 0.000 0.00 0.76 - - - Lepadogaster lepadogaster 0.000 0.20 0.03 0.000 0.20 0.03 - - - Ctenolabrus rupestris 0.000 0.00 0.80 0.000 0.01 0.74 - - - Labrus mixtus -0.001 0.08 0.18 0.000 0.04 0.34 - - - Labrus bergylta -0.003 0.14 0.08 0.000 0.21 0.03 - - - Dicentrachus labrax 0.002 0.12 0.09 0.001 0.14 0.07 -0.834 0.06 0.47 Mullus surmuletus 0.003 0.00 0.83 0.003 0.23 0.02 0.514 0.09 0.26 Serranus cabrilla 0.000 0.01 0.60 0.000 0.01 0.61 -0.776 0.14 0.32 Pagellus spp. 0.000 0.00 1.00 0.000 0.01 0.61 1.051 0.06 0.57 Spondyliosoma cantharus 0.002 0.16 0.05 0.002 0.18 0.04 -0.223 0.00 0.93 Chirolophis ascanii 0.000 0.05 0.30 0.000 0.05 0.30 - - - Echiichthys vipera 0.000 0.04 0.34 0.000 0.03 0.39 - - - Trachinus draco 0.000 0.00 0.91 0.000 0.00 0.91 - - - Arnoglossus spp. -0.163 0.02 0.56 -0.003 0.06 0.26 -0.223 0.13 0.11 Glyptocephalus cynoglossus 0.002 0.17 0.04 0.001 0.15 0.06 0.273 0.01 0.87 Hippoglossus hippoglossus 0.000 0.08 0.19 0.000 0.08 0.19 - - - Limanda limanda 0.188 0.11 0.11 0.005 0.33 <0.001 -0.168 0.08 0.19 Microstomus kitt 0.039 0.17 0.05 0.001 0.04 0.38 0.062 0.00 0.80 Platichthys flesus 0.039 0.17 0.04 0.002 0.09 0.17 1.131 0.50 0.01 Pleuronectes platessa 0.085 0.45 <0.001 0.004 0.26 0.01 -0.143 0.01 0.68
32 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Abundance Abundance Total Length (cm) (CPUE) (frequency of occurrence) Slope r2 p Slope r2 p Slope r2 p
Lepidorhombus whiffiagonis -0.004 0.28 0.01 -0.002 0.30 0.01 -0.726 0.07 0.50 Phrynorhombus spp. 0.040 0.14 0.07 0.005 0.12 0.09 -0.102 0.10 0.21 Scophthalmus maximus -0.001 0.05 0.29 -0.001 0.03 0.40 -0.772 0.05 0.40 Scophthalmus rhombus -0.001 0.01 0.66 -0.001 0.02 0.55 -0.347 0.01 0.73 Zeugopterus punctatus 0.001 0.01 0.69 0.000 0.05 0.30 -0.100 0.05 0.66 Buglossidium luteum 0.011 0.02 0.53 0.004 0.22 0.02 0.290 0.04 0.53 Microchirus variegatus 0.195 0.14 0.07 0.001 0.02 0.54 0.398 0.06 0.36 Solea solea 0.000 0.00 0.95 0.000 0.00 0.82 -0.656 0.23 0.03 Agonus cataphractus 0.001 0.04 0.34 0.000 0.03 0.45 - - - Cyclopterus lumpus 0.000 0.05 0.30 0.000 0.05 0.30 - - - Chelidonichthys gurnardus -0.312 0.19 0.04 -0.002 0.03 0.41 0.056 0.00 0.82 Chelidonichthys lastoviza -0.045 0.43 <0.001 -0.006 0.45 <0.001 0.966 0.21 0.09 Chelidonichthys cuculus 0.363 0.05 0.31 0.001 0.01 0.70 -0.315 0.08 0.20 Chelidonichthys lucerna 0.003 0.03 0.39 0.000 0.00 0.95 0.732 0.10 0.27 Capros aper -0.061 0.19 0.04 -0.004 0.40 <0.001 -1.894 0.90 <0.001 Zeus faber -0.005 0.00 0.92 -0.003 0.09 0.16 0.028 0.00 0.95
33 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 8 – Regressions of sea-surface temperature and species abundance of demersal fish 1913-2001. Trends (linear regressions) of mean annual abundance (CPUE) and frequency of occurrence against temperature (mean annual SST of previous two years, Hadley Centre data). The intention is to isolate species showing trends, rather than to infer significant relationships, hence no attempts have been made to remove temporal autocorrelation or correct for multiple comparisons have been made.
Mean abundance (CPUE) Frequency of occurrence 2 2 slope r p slope r p
Galeorhinus galeus 0.002 0.00 0.92 -0.001 0.00 0.97 Scyliorhinus stellaris 0.370 0.24 0.01 1.273 0.19 0.03 Scyliorhinus canicula 0.675 0.30 0.01 16.208 0.07 0.22 Mustelus mustelus -0.008 0.00 0.76 -0.017 0.01 0.70 Mustelus asterias -0.016 0.00 0.74 -0.032 0.01 0.60 Squalus acanthias -0.294 0.10 0.14 -26.657 0.17 0.04 Raja / Leucoraja spp. 0.118 0.01 0.69 -1.553 0.01 0.70 Squatina squatina 0.041 0.19 0.03 0.041 0.20 0.03 Torpedo spp. 0.010 0.09 0.14 0.010 0.09 0.14 Conger conger 0.401 0.19 0.03 0.672 0.19 0.04 Gadus morhua -0.163 0.02 0.53 -0.256 0.00 0.87 Melanogrammus aeglefinus 0.066 0.12 0.10 0.131 0.16 0.05 Merlangius merlangus 0.687 0.20 0.03 31.692 0.03 0.42 Micromesistius poutassou -0.002 0.00 1.00 -0.303 0.00 0.76 Pollachius pollachius 0.094 0.01 0.59 0.348 0.04 0.36 Pollachius virens 0.005 0.06 0.25 0.009 0.06 0.25 Raniceps raninus 0.006 0.01 0.64 0.006 0.01 0.64 Trisopterus luscus 0.138 0.02 0.56 7.773 0.02 0.57 Trisopterus esmarkii 0.841 0.21 0.03 748.114 0.04 0.36 Enchelyopus cimbrius 0.047 0.01 0.65 0.306 0.01 0.59 Gaidropsarus mediterraneus 0.029 0.03 0.44 0.035 0.02 0.48 Gaidropsarus vulgaris 0.001 0.00 0.94 0.001 0.00 0.94 Molva molva -0.057 0.00 0.81 -0.060 0.00 0.91 Merluccius merluccius 0.710 0.17 0.05 12.911 0.17 0.04 Phycis blennoides 0.012 0.00 0.83 0.018 0.00 0.83 Syngnathus acus 0.102 0.02 0.47 0.310 0.03 0.45 Lophius spp. 0.643 0.15 0.06 2.321 0.03 0.42 Blennius ocellaris 0.118 0.01 0.68 0.243 0.01 0.64 Lipophrys pholis 0.005 0.00 0.79 0.009 0.00 0.79 Callionymus reticulatus -0.023 0.00 0.88 -10.040 0.03 0.42 Callionymus maculatus 0.387 0.03 0.44 2.670 0.01 0.63 Callionymus lyra 0.223 0.05 0.28 95.591 0.03 0.42 Gobiidae 0.112 0.01 0.64 -0.131 0.00 0.88 Cepola macrophthalma 0.525 0.12 0.10 3.599 0.02 0.54 Diplecogaster bimaculata -0.006 0.00 0.91 -0.025 0.01 0.66 Lepadogaster lepadogaster -0.006 0.04 0.32 -0.013 0.07 0.20 Ctenolabrus rupestris 0.022 0.01 0.71 0.036 0.01 0.73 Labrus mixtus -0.035 0.11 0.12 -0.263 0.23 0.02 Labrus bergylta -0.039 0.10 0.14 -0.326 0.08 0.17 Dicentrachus labrax 0.147 0.06 0.24 0.221 0.04 0.36 Mullus surmuletus 0.323 0.12 0.10 1.194 0.01 0.65 Serranus cabrilla 0.031 0.00 0.78 0.046 0.00 0.75 Pagellus spp. 0.156 0.12 0.10 0.841 0.13 0.08 Spondyliosoma cantharus 0.116 0.04 0.35 0.172 0.03 0.40 Chirolophis ascanii 0.003 0.00 0.85 0.003 0.00 0.85 Echiichthys vipera 0.052 0.24 0.01 0.076 0.27 0.01 Trachinus draco 0.002 0.00 0.83 0.002 0.00 0.83 Arnoglossus spp. 0.414 0.04 0.38 14.927 0.00 0.75 Glyptocephalus cynoglossus -0.030 0.00 0.82 -0.021 0.00 0.88 Hippoglossus hippoglossus -0.012 0.02 0.51 -0.012 0.02 0.51 Limanda limanda -0.014 0.00 0.96 -15.251 0.03 0.44 Microstomus kitt 0.109 0.01 0.65 1.478 0.01 0.66 Platichthys flesus 0.228 0.04 0.37 2.860 0.03 0.38 Pleuronectes platessa -0.024 0.00 0.92 3.480 0.03 0.43
34 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Mean abundance (CPUE) Frequency of occurrence 2 2 slope r p slope r p
Lepidorhombus whiffiagonis -0.266 0.36 <0.001 -0.775 0.41 <0.001 Phrynorhombus spp. 0.519 0.06 0.25 3.149 0.03 0.40 Scophthalmus maximus 0.266 0.12 0.10 0.263 0.08 0.19 Scophthalmus rhombus 0.603 0.21 0.02 1.268 0.25 0.01 Zeugopterus punctatus -0.039 0.02 0.56 0.036 0.00 0.86 Buglossidium luteum 0.277 0.03 0.39 -0.256 0.00 0.93 Microchirus variegatus 0.453 0.09 0.15 11.665 0.02 0.53 Solea solea 0.175 0.02 0.50 0.095 0.00 0.90 Agonus cataphractus 0.041 0.03 0.43 0.087 0.03 0.41 Cyclopterus lumpus -0.015 0.01 0.62 -0.015 0.01 0.62 Chelidonichthys gurnardus -0.561 0.15 0.06 -25.917 0.05 0.30 Chelidonichthys lastoviza -0.341 0.05 0.31 -4.236 0.14 0.07 Chelidonichthys cuculus 0.027 0.00 0.94 -19.691 0.01 0.74 Chelidonichthys lucerna 0.225 0.11 0.11 0.330 0.01 0.58 Capros aper -0.616 0.31 <0.001 -9.372 0.16 0.05 Zeus faber -0.658 0.16 0.05 -7.709 0.04 0.33
35 Project Archiving and analysis of the MBA bottom trawl and benthic MAFF MF0727 title survey data: Unravelling fishing efforts from climate change project code
Annex 9 – GIS representation of Holme sampling sites in the English Channel
Please press enter
36