scholarly journals What caused seven consecutive years of low puerulus settlement in the western rock lobster fishery of Western Australia?

2014 ◽  
Vol 72 (suppl_1) ◽  
pp. i49-i58 ◽  
Author(s):  
Simon de Lestang ◽  
Nick Caputi ◽  
Ming Feng ◽  
Ainslie Denham ◽  
James Penn ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Egg Production ◽  
Early Stage ◽  
Larval Growth ◽  
Rock Lobster ◽  
Offshore Water ◽  
Storm Activity ◽  
Recruitment Failure ◽  
Lobster Fishery ◽  
Timing Of Spawning

Abstract Puerulus settlement in the western rock lobster fishery has remained below average for seven consecutive years (2006/2007–2012/2013), with 2008/2009 being the lowest in over 40 years. Examination of the timing of the start of spawning using fishery-independent data since the mid-2000s indicated that spawning has been occurring earlier. The low settlement appears related to higher water temperatures at the time of the onset of spawning (October) since the mid-2000s. Statistical analysis shows that the most (71%) of the variation in puerulus settlement was explained by the timing of spawning, storm activity during autumn/spring, and offshore water temperatures in February. Earlier spawning may cause a mismatch with other environmental factors such as peaks in ocean productivity and/or storms that assist the larvae return to the coast and offshore water temperatures that help the early stage larval growth. These variables produced a plausible hypothesis to explain the decline in puerulus settlement for these 7 years, including the recruitment failure of 2008/2009. They also predicted the substantial improvement in settlement for 2013/2014. Egg production levels did not to have a significant relationship with puerulus settlement levels after taking environmental variables into account. Further verification with additional years is required to see whether this relationship is maintained. Global climate change may influence these environmental factors: the timing of spawning is influenced by water temperature and there has been a reduced trend of autumn to spring storms off southwest Australia.

Restructuring the Tasmanian rock-lobster fishery - the effect of two years of management under individual transferable quotas

2001 ◽  
Vol 52 (8) ◽  
pp. 1641 ◽  
Author(s):  
Wes Ford ◽  
Wes Ford
Keyword(s):  
Egg Production ◽  
Fishing Effort ◽  
Rock Lobster ◽  
Quota System ◽  
Individual Transferable Quotas ◽  
Fishing Vessels ◽  
Early Results ◽  
Lobster Fishery ◽  
Quota Management ◽  
One Year

Individual transferable quotas were successfully introduced into the Tasmanian rock-lobster fishery in 1998. In the two years since, significant industry restructuring has occurred. The move to quota management was intended to meet two key objectives: to reduce the catch to a sustainable level, allowing the stock to rebuild, and to provide a mechanism whereby the industry could achieve economic sustainability. The quota system has achieved early results on both the sustainability and restructuring objectives and is now well accepted and supported by the vast majority of fishers and licence holders. Its effect has been to reduce fishing effort by 29% and number of fishing vessels by 23%, and the reduction in catch has resulted in a 6% increase in the estimated biomass and substantial increases in egg production after one year. Fishers now spend fewer days at sea, and catch rates are improving. These changes are reducing fishing costs, which in time should increase profitability. Social costs of introducing quotas are that fewer fishers are employed on vessels and that fishers now find it harder and more expensive to lease a fishing licence. These costs must be factored into any assessment of the industry.

scholarly journals Changes in the lease and permanent sale quota markets of a rock lobster fishery in response to stock abundance

2015 ◽  
Vol 72 (5) ◽  
pp. 1555-1564 ◽  
Author(s):  
Rafael León ◽  
Caleb Gardner ◽  
Ingrid van Putten ◽  
Klaas Hartmann
Keyword(s):  
Granger Causality Test ◽  
Economic Rent ◽  
Rock Lobster ◽  
Markov Modelling ◽  
Causality Test ◽  
Individual Transferable Quotas ◽  
Theoretical Pattern ◽  
Lobster Fishery ◽  
Trade Market ◽  
Stock Abundance

AbstractEffective individual transferable quotas (ITQ) systems rebuild stocks and allow transfer of quotas to more efficient operators. This process requires functional markets for both quota sales and temporary quota leases. These markets are expected to respond to changes in economic rent from the fishery, which is influenced by stock abundance and the international rock lobster price. This research used multistate Markov modelling and Granger causality test to examine changes in the permanent and temporary quota trade in the Tasmanian rock lobster fishery quota market, during periods of both increasing and decreasing stock abundance. The permanent quota trade market was more active during the period of stock growth, while the quota lease market was active in both periods of stock growth and decline. In contrast to theoretical trends in ITQ fisheries, trades in both markets were not linked to the technical efficiency (i.e. catching capability) of operators, but were more driven by the quota owners' financial capacity (i.e. number of owned quotas). Prolonged and unexpected stock decline affected the quota market so that it deviated from the theoretical pattern of ITQ fisheries. Operators previously active in the market reduced their activity, while smaller operators and firms that previously had not traded became more active, so the fleet expanded with smaller operators entering.

Climate Vulnerability and its Perceived Impact on the Namibian Rock Lobster Fishery

2021 ◽  
pp. 1843-1863
Author(s):  
Johannes A. Iitembu ◽  
Paulus Kainge ◽  
Warwick H. H. Sauer
Keyword(s):  
Rock Lobster ◽  
Climate Vulnerability ◽  
Lobster Fishery ◽  
Perceived Impact

Contrasting environmental factors drive bacterial and eukaryotic community successions in freshly deglaciated soils

2019 ◽  
Author(s):  
Ajmal Khan ◽  
Weidong Kong ◽  
Said Muhammad ◽  
Fei Wang ◽  
Guoshuai Zhang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Early Stage ◽  
Microbial Colonization ◽  
First Year ◽  
The Tibetan Plateau ◽  
Community Succession ◽  
Soil Factors ◽  
Eukaryotic Community ◽  
Gene Copies ◽  
Late Stages

ABSTRACT Glacier retreats expose deglaciated soils to microbial colonization and succession, however, the differences in drivers of bacterial and eukaryotic succession remain largely elusive. We explored soil bacterial and eukaryotic colonization and yearly community succession along a deglaciation chronosequence (10-year) on the Tibetan Plateau using qPCR, T-RFLP, and sequencing of clone libraries. The results exhibited that bacteria and eukaryotes rapidly colonized the soils in the first year of deglaciation, thereafter slowly increasing from 107 up to 1010 and 1011 gene copies g−1 soil, respectively. Bacterial and eukaryotic community changes were observed to group into distinct stages, including early (0–2 year old), transition (3–5 year old) and late stages (6–10 year old). Bacterial community succession was dominantly driven by soil factors (47.7%), among which soil moisture played a key role by explaining 26.9% of the variation. In contrast, eukaryotic community succession was dominantly driven by deglaciation age (22.2%). The dominant bacterial lineage was Cyanobacteria, which rapidly decreased from the early to the transition stage. Eukaryotes were dominated by glacier-originated Cercozoa in early stage soils, while green algae Chlorophyta substantially increased in late stage soils. Our findings revealed contrasting environmental factors driving bacterial and eukaryotic community successions.

scholarly journals Evaluating the ecosystem effects of variation in recruitment and fishing effort in the western rock lobster fishery

2013 ◽  
Vol 145 ◽  
pp. 128-135 ◽  
Author(s):  
Hector Lozano-Montes ◽  
Neil R. Loneragan ◽  
Russ Babcock ◽  
Nick Caputi
Keyword(s):  
Fishing Effort ◽  
Rock Lobster ◽  
Ecosystem Effects ◽  
Lobster Fishery
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