Lobster reserves in coastal Skagerrak: a field laboratory for science and management
Even Moland Esben M. Olsen, Alf R. Kleiven, Halvor Knutsen, Sigurd H. Espeland, Jan Atle Knutsen
Institute of Marine Research (IMR), Flødevigen European lobster (Homarus gammarus)
• Habitat: prefers rocky habitat, from shallow water to > 50 m • Feeding ecology: omnivorous • Life cycle: pelagic larvae hatch in spring from eggs carried by females during incubation (9 –11 months). Postlarvae settle after a 3 –8 week pelagic larval duration • Fishery: caught by traps during a two month season (October – November) by commercial and recreational fishers • Conservation status: (Norway) red listed (NT) in 2006 & 2010 based on fisheries data indicative of historically low abundance Catch per unit effort (100 traps day-1) Lobster fisheries data,
Norway Atlantic cod (Gadus morhua) • Commercial and recreational target species • Minimum legal size (MLS) 40 cm • Coastal cod in Skagerrak is genetically structured into local populations on a scale of 30 km or less Jorde et al. 2007, MEPS 343: 229‐237
Photo by Øystein Paulsen used with permission. IMR Flødevigen beach seine time series: 1919 ‐ present
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10 Cod per haul 0 16 1920 1940 1960 1980 2000
14 Sea temperature
1920 1940 1960 1980 2000
Foto: Ø. Paulsen What do we need to quantify effects of protection ?
1. Control areas: areas that are not protected, where we conduct the same type of sampling 2. ’before‐data’: sampling prior to impact –to describe the situation before protection was introduced 3. Replication: within and among protected and unprotected sites 4. Time
Norway RC R Bolærne C Bolærne 59 o N Kvernskjær Kvernskjær Risør R Flødevigen R Skagerrak C Flødevigen 10 o E Risør Four experimental MPAs/ lobster reserves in Skagerrak designated September 2006: ban on standing gear (only hook and line gear types allowed). Designation of the lobster reserves sparked several studies…
…in addition to the long term monitoring (recently published) • One of the northernmost examples of MPA effects to date • Two key species • A replicated BACI‐design is still novel and newsworthy in MPA science How did people feel about the lobster reserves?
Norway RC R Bolærne C Bolærne 59 o N Kvernskjær Kvernskjær Risør R Flødevigen R Skagerrak C Flødevigen 10 o E Risør Questionaire survey conducted in Arendal (Flødevigen) and Hvaler (Kvernskjær) 2007: 83 % expected a positive effect on lobster within the areas 70 % expected a positive effect on lobster beyond the areas 88 % of respondents were positive to the idea of using reserves in management of lobster 98 % reported that they had not been involved in the establishment process, but
many voiced a wish toPettersen be involvedet al. 2009, inIn: Integratedthe even Coastalt of Zonfuturee Man aprocessesgement, Wiley‐Blackwell pp. 178‐188 Long term monitoring: experimental fishing
• Three replicate MPA/ control area pairs
Bolærne (b) • BACI design • 100 pot hauls in MPAs and control areas Kvernskjær (c) spread over four days (25 traps x 4) Flødevigen (a) Mean relative change in CPUE MPA established MPAs ≈ 245 %
control areas Before ≈ 87 % -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
2006 2007 2008 2009 2010
Moland et al. 2013, PRSB 280: 20122679 Long term monitoring: experimental fishing
Effect of protection on catch‐per‐unit‐effort (CPUE) of lobster in the three replicate MPA – control area pairs.
Flødevigen Bolærne Kvernskjær
a Before MPA establ. b Before MPA establ. c Before MPA establ. Lobsters per trap per Lobsters 0.00.51.01.52.02.53.03.5 0.00.51.01.52.02.53.03.5 0.00.51.01.52.02.53.03.5 2004 2006 2008 2010 2004 2006 2008 2010 2004 2006 2008 2010 White bar = control area; grey bar = MPA
Moland et al. 2013, PRSB 280: 20122679 Long term monitoring: experimental fishing
Effect of protection on mean body size (TL) of lobster in the three replicate MPA – control area pairs. 28 28 a Before MPA est. 28 b Before MPA establ. c Before MPA establ. 26 26 26 MLS 24 24 24 Lobster body size, cm size, body Lobster 22 22 22
2004 2005 2006 2007 2008 2009 2010 2004 2005 2006 2007 2008 2009 2010 2004 2005 2006 2007 2008 2009 2010
Blue symbols = control area; green symbols = MPA
Moland et al. 2013, PRSB 280: 20122679 Effect on coastal Atlantic cod (Gadus morhua)
Arendal –MPA(●) Experimental white bar = NE control fishing, 2010 light grey bar = Arendal – control example: ● = location of green bar = Arendal –MPA gear (fyke nets) dark grey bar = SW control used to sample cod during the 2010 A Arendal – control (●) field season. Probablity of catch Probablity of 0.4 0.6 0.8 1.0
2005 2006 2007 2008 2009 2010
B
Lillesand –SW control Mean size, cm 30 35 40 45 50 2005 2006 2007 2008 2009 2010 C Risør –NE control 90% percentile, cm percentile, 90% 40 45 50 55 60 65 2005 2006 2007 2008 2009 2010 Moland et al. 2013, PRSB 280: 20122679 ? ! 3 1
? ! 4 2
Build‐up of higher density (1) and increased mean size (2) has been demonstrated for lobster and cod in experimental MPAs in Skagerrak. It is expected that an increase in density inside MPAs will result in spill‐ over (3), whereas increased density and mean size (1 + 2) will result in increased spawning potential in MPAs relative to adjacent areas, potentially resulting in net export of eggs, larvae and/or juveniles (4) out of MPAs/ marine reserves (recruitment effect). Norway 23 lobsters tagged in
Kv Flødevigen (Fl) and 34
Ri lobsters tagged in Swe. Kvernskjær (Kv) lobster Fl Kå Skagerrak reserve in 2006. Recovered tags yielded up 1 yr of depth and Den. temperature data.
Time of day
20 a 20 b 10 10 0 0 All data from 10 -10 -10 -20 -20 Depths inside reserves recaptured tags/ -30 -30 -40 -40 lobsters -50 -50 Depths outside reserves SNJMMJS SNJMMJS 20 c 20 d 10 10 0 0 -10 -10 -20 -20 -30 -30 -40 -40 -50 -50 SNJMMJS SNJMMJS 20 e 20 f 10 10 0 0 -10 -10 -20 -20 -30 -30 -40 -40 -50 -50 SNJMMJS SNJMMJS 20 g 20 h 10 10
Depth (m) and temperature (C) and temperature (m) Depth 0 0 -10 -10 -20 -20 -30 -30 -40 -40 -50 -50
SNJMMJS SNJMMJS 20 i 20 j 10 10 0 0 -10 -10 -20 -20 -30 -30 -40 -40 -50 -50
SNJMMJS SNJMMJS Observation period (month) Moland et al. 2011. MEPS 429: 197‐207 Acoustic tracking: kernel home range (95%UD) 1 for 19 lobsters tracked 2 during 2006 – 2007 in the 19 15 20 Flødevigen MPA 17 8 • Lobster home range areas ranged from 0.6 –4 % of 13 total MPA area (1 km2). • No significant difference 3 18 between males, non‐ 9 ovigerous females and 4 ovigerous females for an 14 overlapping observation 10 period of 242 d. 16
5 12 11 500 m 6 Moland et al. 2011. CJFAS 68:1197‐1210 Main conclusions and implications
•Stakeholder groups with a strong sense of ownership towards a resource can be supportive to protection as a management measure. •European lobster populations may recover to natural levels (density/ size‐ and age distribution) in relatively small reserves/ MPAs. • Effect of partial protection on density and body size of cod in the Flødevigen MPA (1 km2) indicate that small scale protection may confer benefits to this iconic species. •Limited home ranges and high site fidelity are strong indications that coastal reserves of limited size can be designed to afford long‐term protection to portions of the European lobster population. Funding was provided by the Institute of Marine Research, the Swedish Board of Fisheries, the Research Council of Norway (‘Oceans & Coastal Areas’ programme), and by the EU and Norwegian government through the ‘INTERREG III A’ programme.
Special thanks to Mats Ulmestrand, Hassse Hallbäck, Svein Erik Enersen, Kate Enersen, Hanne Sannæs, Kristian Andvord, Mats Huserbråten, Sebastian Bosgraaf, Pauline Garrigou, Victor Bret and Einar Dahl.