Size-based species interactions shape herring and cod population dynamics in the face of exploitation
Denderen, P.D. van; Kooten, T. van - \ 2013
Ecosphere 4 (2013)10. - ISSN 2150-8925
north-sea cod - clupea-harengus - intraguild predation - prey - model - recruitment - recovery - biomass - management - fisheries
Size-specific competition and predation interactions often link the population dynamics of fish species in their response to exploitation. The effects of harvesting on interacting fish species is of increasing relevance as more and more fish populations worldwide are reduced by fishing. When stocks are harvested, effects of harvesting may percolate to populations of other species with which it interacts through competition, predation, etcetera. When multiple species are exploited, this can lead to interactions between fisheries, mediated by ecological interactions. Nevertheless, most fish stocks are managed using a single-species framework. We studied how single-species explanations of historical population dynamics work out when size-based interactions between harvested species are taken into account. We have taken as a case study the dynamics of cod (Gadus morhua) and herring (Clupea harengus) in the North Sea. These dynamics are generally considered to be shaped by fishing pressure on and food availability to single species. Our results indicate that the explanatory power of these factors is maintained with the inclusion of species interactions, but the processes leading to the observed patterns are altered as the fates of the species are interdependent. The sign and magnitude of the interaction between the species depends on the state of the populations, their exploitation history and environmental factors such as resource productivity. This context-dependent response to changing fishery intensity has important ramifications for management. We show that management plans for the exploitation of either one of these species, or for the recovery of North Sea cod, which do not account for these subtle interactions, may fail or backfire. Hence, such interactions link the fate of these species in complex ways, which must be taken into consideration for successful management of their exploitation, including harvesting at maximum sustainable yield, as we move towards an ecosystem-based management of marine fisheries.
Dietary overlap between the potential competitors herring, sprat and anchovy in the North Sea
Raab, K.E. ; Nagelkerke, L.A.J. ; Boeree, C. ; Rijnsdorp, A.D. ; Temming, A. ; Dickey-Collas, M. - \ 2012
Marine Ecology Progress Series 470 (2012). - ISSN 0171-8630 - p. 101 - 111.
engraulis-encrasicolus l. - central baltic sea - clupea-harengus - feeding-behavior - intraguild predation - trophic interactions - population-dynamics - mediterranean sea - fish eggs - irish sea
European anchovy Engraulis encrasicolus increased its abundance and distribution in the North Sea during the mid-1990s and may consume similar zooplankton to and/or compete with other occupants of the North Sea like herring Clupea harengus and sprat Sprattus sprattus. The diets of adult anchovy, sprat and juvenile herring of comparable sizes, sampled close in time and space, were compared to understand how the 3 species prey on zooplankton and establish whether their diets overlap or not. Anchovy was found to be more generalist, consuming a higher diversity of prey items. Herring was more specialized, with low diversity of food items. Sprat was intermediate between anchovy and herring. The dietary overlap between anchovy and sprat was highest, followed by herring and sprat before anchovy and herring. The mean weight of stomach contents did not differ between species. We conclude that of the 3 species, anchovy is likely to be the least affected by changing plankton communities.
Temporal changes in plankton of the North Sea: community shfits and environmental drivers
Alvarez-Fernandez, S. ; Lindeboom, H.J. ; Meesters, H.W.G. - \ 2012
Marine Ecology Progress Series 462 (2012). - ISSN 0171-8630 - p. 21 - 38.
long-term changes - regime shifts - phytoplankton biomass - temperature-changes - calanoid copepods - clupea-harengus - atlantic - climate - variability - ecology
This paper analyses long-term and seasonal changes in the North Sea plankton community during the period 1970 to 2008. Based on Continuous Plankton Recorder (CPR) data covering 38 yr, major changes in both phytoplankton and zooplankton abundance and community structure were identified. Regime changes were detected around 1978, 1989 and 1998. The first 2 changes have been discussed in the literature and are defined as a cold episodic event (1978) and a regime shift towards a warm dynamic regime (1989). The effect of these 2 regime changes on plankton indicators was assessed and checked against previous studies. The 1998 change represents a shift in the abundance and seasonal patterns of dinoflagellates and the dominant zooplankton group, the neritic copepods. Furthermore, environmental factors such as air temperature, wind speed and the North Atlantic water inflow were identified as potential drivers of change in seasonal patterns, and the most-likely environmental causes for detected changes were assessed. We suggest that a change in the balance of dissolved nutrients driven by these environmental factors was the cause of the latest change in plankton community structure, which in turn could have affected the North Sea fish community
Characterization of herring populations west of the British Isles: an investigation of mixing based on otolith microchemistry
Geffen, A.J. ; Nash, R.D.M. ; Dickey-Collas, M. - \ 2011
ICES Journal of Marine Science 68 (2011)7. - ISSN 1054-3139 - p. 1447 - 1458.
clupea-harengus - north-sea - fisheries science - atlantic - connectivity - management - fish - cod - metapopulations - diversity
Herring along the west coast of the British Isles are managed and assessed as a series of discrete stocks. The relationship between the spawning components, mixed (feeding) aggregations, and juveniles in nursery areas for these stocks was modelled by discriminant analysis and integrated stock mixture analysis based on otolith elemental composition data. The relative elemental concentrations produced otolith signals corresponding to three main groupings of nursery-ground fish representing the Irish Sea, Scottish sea lochs, and the Minch. There were significant differences among spawning groups in the otolith concentrations of Li, Na, Mg, Mn, Sr, and Ba. Inclusion of length-at-age information improved the classification rates, ranging overall from 35 to 100%. Spawning groups consist of individuals from a number of different nursery areas and originate from several different management areas. Each of the mixed aggregations contained at least three spawning components. Results suggest that most west coast herring belong to interconnected populations subject to mixing and that populations are not discrete, so the current practice of assessments based on individual spawning components will probably not provide sufficiently robust information for management advice. The complexity of herring populations needs to be considered for both fisheries and coastal-zone management
Variability in transport of fish eggs and larvae. I. Modelling the effects of coastal reclamation
Erftemeijer, P.L.A. ; Beek, J.K.L. van; Bolle, L.J. ; Dickey-Collas, M. ; Los, H.F.J. - \ 2009
Marine Ecology Progress Series 390 (2009). - ISSN 0171-8630 - p. 167 - 181.
sole solea-solea - southeastern north-sea - wadden sea - pleuronectes-platessa - clupea-harengus - plaice eggs - impact - areas - consequences - recruitment
Dispersal of eggs and larvae of herring, plaice and sole in the southern North Sea was studied by modelling using real-time hydrodynamic forcing (with wind, air pressure and river discharge) and species-specific knowledge of larval behaviour (incorporating salinity triggers), temperature-dependent growth and spawning characteristics. Larval transport was simulated using a finite-volume advection-diffusion model (Delft3D-WAQ) coupled to a 3-dimensional hydrodynamic model (Delft3D-FLOW). Model parameter settings were refined following a sensitivity analysis. Validation of modelled hydrodynamics and larval distribution patterns showed broad agreement with field data. Differences in model results for larval distribution, transport success and timing of arrival at nursery grounds between baseline conditions and a scenario that incorporated a proposed 1000 ha coastal reclamation (protruding 6 to 7 km from the Dutch coastline) for the expansion of the Port of Rotterdam (Maasvlakte-2) were insignificant in comparison to the interannual variability in larval dispersal for these species. Results suggest that effects of the proposed coastal reclamation on the transport success of fish larvae (flatfish and herring), an issue over which public stakeholders had expressed concern, will be negligible.
Lumpers or splitters? Evaluating recovering and management plans for metapopulations of herring
Kell, L.T. ; Dickey-Collas, M. ; Hintzen, N.T. ; Nash, R.D.M. ; Pilling, G.M. - \ 2009
ICES Journal of Marine Science 66 (2009)8. - ISSN 1054-3139 - p. 1776 - 1783.
clupea-harengus - north-sea - populations - fisheries - strategies - fish - west
The long-term management of a stock representing a metapopulation has been simulated in a case study loosely based upon herring to the west of the British isles, where stocks are currently assessed and managed by management area, although there is evidence of mixing between stocks (in terms of connectivity, migrations, and exploitation). The simulations evaluate scientific advice (based on virtual population analysis, VPA) and the sustainability of fishing under two population-structure scenarios, corresponding either to discrete stocks, which only mix on the feeding grounds, or where diffusion between stocks takes place. The ability of stock assessment to monitor stock status and exploitation levels was evaluated for defining stocks based on fishing areas and for stocks that combined fishing areas. The study showed that assessment based on VPA of the metapopulation could fail to detect overexploitation of stocks and fail to detect and distinguish between the effects of exploitation and regime shifts
Recruitment of lesser sandeel Ammodytes marinus in relation to density dependence and zooplankton composition
Deurs, M. van; Hal, R. van; Tomczak, M.T. ; Jonasdottir, S.H. ; Dolmer, P. - \ 2009
Marine Ecology Progress Series 381 (2009). - ISSN 0171-8630 - p. 249 - 258.
north-atlantic oscillation - vertical-distribution - calanus-finmarchicus - c-helgolandicus - clupea-harengus - baltic sea - bottom-up - fish - raitt - food
Recent recruitment failure of lesser sandeel Ammodytes marinus, a key prey fish in the North Sea, followed by several years of low spawning stock biomass, prompted us to investigate factors influencing the recruitment of this species. We tested 2 hypotheses that relate to ecological mechanisms of recruitment regulation in lesser sandeel: (1) a positive spawning stock¿recruitment relationship is decoupled in years associated with high abundances of age-1 sandeels and (2) the survival success of early larvae depends specifically on the abundance of Calanus finmarchicus and not C. helgolandicus. The findings of the present study supported both hypotheses and resulted in a multiple linear recruitment model with pronounced predictive capabilities. The model includes interactions between age-1 abundance and spawning stock biomass, plus the effect of C. finmarchicus abundance, and it explained around 65% of the inter-annual variation in recruitment in contrast to only 12% by a traditional Ricker curve. We argue that early egg production in C. finmarchicus supports the survival of larvae, and that climate-generated shifts in the Calanus species composition lead to a mismatch in timing between food availability and the early life history of lesser sandeels.
Effects of acoustic alarms, designed to reduce small cetacean bycatch in gillnet fisheries, on the behaviour of North Sea fish species in a large tank
Kastelein, R.A. ; Heul, S. van der; Veen, J. van der; Verboom, W.C. ; Jennings, N. ; Haan, D. de; Reijnders, P.J.H. - \ 2007
Marine Environmental Research 64 (2007)2. - ISSN 0141-1136 - p. 160 - 180.
porpoises phocoena-phocoena - cod gadus-morhua - geophysical survey device - rockfish sebastes - startle response - clupea-harengus - floating pen - sounds - hearing - ultrasound
World-wide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9¿13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish.
Chemical and sensory evaluation of crude oil extracted from herring byproducts from different processing operations
Aidos, I.M. ; Schelvis-Smit, A.A.M. ; Veldman, M. ; Luten, J.B. ; Padt, A. van der; Boom, R.M. - \ 2003
Journal of Agricultural and Food Chemistry 51 (2003)7. - ISSN 0021-8561 - p. 1897 - 1903.
lipid oxidation - clupea-harengus - fatty-acids - alpha-tocopherol - by-products - fish oils - stability - fluorescence - storage - fillets
Fish oils extracted from marinated herring (frozen and unfrozen) byproducts and maatjes herring byproducts were evaluated on their chemical and sensory properties. The obtained crude oils had very low content of copper (
Quality of crude fish oil extracted from herring byproducts of varying states of freshness
Aidos, I.M. ; Padt, A. van der; Boom, R.M. ; Luten, J.B. - \ 2003
Journal of Food Science 68 (2003)2. - ISSN 0022-1147 - p. 458 - 465.
sardine sardina-pilchardus - fluorescence detection - lipid oxidation - clupea-harengus - frozen storage - histamine - temperature - fillets - stability - amines
Herring byproducts were stored at 2 and 15degreesC for up to 72 h. Over time, significant increases of total volatile bases (TVB), histamine, putrescine, cadaverine, and tyramine were detected. However, only tyramine and TVB levels were temperature-dependent. The level of total polyunsaturated fatty-acids (PUFAs) was constant. Longer byproducts storage gave rise to an oil with higher levels of free fatty acids, eicosapentaenoic acid (EPA), docosahexaenoic acid (DRA), and total PUFAs, while fluorescent compounds were lower. A higher storage temperature led to oil higher in alpha-tocopherol and EPA levels and lower in anisidine value. Surprisingly, the oil with the highest content of PUFAs was not produced from the freshest byproducts, and oil With low oxidation products can be extracted from stored byproducts.