Reassessing regime shifts in the North Pacific: incremental climate change and commercial fishing are necessary for explaining decadal-scale biological variability

2013 ◽  
Vol 20 (1) ◽  
pp. 38-50 ◽  
Author(s):  
Michael A. Litzow ◽  
Franz J. Mueter ◽  
Alistair J. Hobday
Author(s):  
Fumiaki Kobashi ◽  
Toshiya Nakano ◽  
Naoto Iwasaka ◽  
Tomomichi Ogata

AbstractDecadal-scale variability of the North Pacific subtropical mode water (STMW) and its influence on the pycnocline are examined by analyzing Japan Meteorological Agency (JMA) repeat hydrographic observations along the 137°E meridian from 1972 to 2019, with a particular focus on the summer season when the seasonal upper pycnocline develops above the STMW. The STMW appears between 20° and 32°N at 137°E, with the thickness varying on decadal timescales of approximately 9–15 years. Argo float observations suggest that the observed change in the STMW thickness originates in the wintertime mixed layer south of the Kuroshio Extension in the preceding year. The STMW has a substantial impact on the pycnocline. The presence of thick STMW shoals the upper pycnocline, occasionally concurrent with the deepening of the lower main pycnocline. The change is robust in the upper pycnocline, where the heaving of isopycnal surfaces occurs with density anomalies up near the surface. The subtropical front (STF) at subsurface depths, which is associated with a northward shoaling of the upper pycnocline and is maintained by the STMW in the climatology, also changes on decadal timescales. A thick STMW increases the northward shoaling of the upper pycnocline and intensifies the STF. On decadal timescales, the STF variations are accounted for by the STMW-induced change in the upper pycnocline slope. The change in the STF due to mode waters is consistent with previous findings from numerical models.


2019 ◽  
Vol 6 (3) ◽  
pp. 181463 ◽  
Author(s):  
R. Cartwright ◽  
A. Venema ◽  
V. Hernandez ◽  
C. Wyels ◽  
J. Cesere ◽  
...  

Alongside changing ocean temperatures and ocean chemistry, anthropogenic climate change is now impacting the fundamental processes that support marine systems. However, where natural climate aberrations mask or amplify the impacts of anthropogenic climate change, identifying key detrimental changes is challenging. In these situations, long-term, systematic field studies allow the consequences of anthropogenically driven climate change to be distinguished from the expected fluctuations in natural resources. In this study, we describe fluctuations in encounter rates for humpback whales, Megaptera novaeangliae , between 2008 and 2018. Encounter rates were assessed during transect surveys of the Au'Au Channel, Maui, Hawaii. Initially, rates increased, tracking projected growth rates for this population segment. Rates reached a peak in 2013, then declined through 2018. Specifically, between 2013 and 2018, mother–calf encounter rates dropped by 76.5%, suggesting a rapid reduction in the reproductive rate of the newly designated Hawaii Distinct Population Segment of humpback whales during this time. As this decline coincided with changes in the Pacific decadal oscillation, the development of the NE Pacific marine heat wave and the evolution of the 2016 El Niño, this may be another example of the impact of this potent trifecta of climatic events within the North Pacific.


2010 ◽  
Vol 3 (11) ◽  
pp. 762-765 ◽  
Author(s):  
E. Di Lorenzo ◽  
K. M. Cobb ◽  
J. C. Furtado ◽  
N. Schneider ◽  
B. T. Anderson ◽  
...  

2013 ◽  
Vol 70 (5) ◽  
pp. 1013-1022 ◽  
Author(s):  
Nan-Jay Su ◽  
Chi-Lu Sun ◽  
André E. Punt ◽  
Su-Zan Yeh ◽  
Gerard DiNardo ◽  
...  

Abstract Su, N.-J., Sun, C.-L., Punt, A. E., Yeh, S.-Z., DiNardo, G., and Chang, Y.-J. 2013. An ensemble analysis to predict future habitats of striped marlin (Kajikia audax) in the North Pacific Ocean. – ICES Journal of Marine Science, 70: 1013–1022. Striped marlin is a highly migratory species distributed throughout the North Pacific Ocean, which shows considerable variation in spatial distribution as a consequence of habitat preference. This species may therefore shift its range in response to future changes in the marine environment driven by climate change. It is important to understand the factors determining the distribution of striped marlin and the influence of climate change on these factors, to develop effective fisheries management policies given the economic importance of the species and the impact of fishing. We examined the spatial patterns and habitat preferences of striped marlin using generalized additive models fitted to data from longline fisheries. Future distributions were predicted using an ensemble analysis, which represents the uncertainty due to several global climate models and greenhouse gas emission scenarios. The increase in water temperature driven by climate change is predicted to lead to a northward displacement of striped marlin in the North Pacific Ocean. Use of a simple predictor of water temperature to describe future distribution, as in several previous studies, may not be robust, which emphasizes that variables other than sea surface temperatures from bioclimatic models are needed to understand future changes in the distribution of large pelagic species.


2001 ◽  
Vol 49 (1-4) ◽  
pp. 227-244 ◽  
Author(s):  
Carrie L. Leonard ◽  
Robert R. Bidigare ◽  
Michael P. Seki ◽  
Jeffrey J. Polovina

2003 ◽  
Vol 11 (2) ◽  
pp. 103-139 ◽  
Author(s):  
Robie W Macdonald ◽  
Brian Morton ◽  
Sophia C Johannessen

Chemical contaminants in the North Pacific Ocean include hydrocarbons, persistent organic pollutants, metals, persistent solids, and domestic pollutants. Here, we review contaminant research conducted over the past decade, finding that the effects of contaminants cannot be considered in isolation from other major factors causing change to North Pacific ecosystems. Climate change, over-fishing, habitat destruction, eutrophication, and the introduction of exotic species interact with one another and alter contaminant pathways. Climate change and over-fishing are perceived as the main threats to the remote northern marginal seas, the central North Pacific, and the west coast of North America, with contaminants engendering local concern, especially in semi-enclosed bodies of water. Climate change receives less attention in Asian waters, probably because widespread habitat destruction and contamination provide, by themselves, an impending ecological disaster. A systematic approach is urgently required to recognize and prioritize the threats to North Pacific coastal ecosystems. This should include box models, case studies, proxy records, and time series. The ocean should be monitored as a system, including physical media (water, sediment) and the full trophic range of the food web, and tissues should be preserved in archives to provide a resource for understanding emerging concerns. Finally, the development of ecological indicators is urgently required to provide a robust warning system based on the health of the marine ecosystems themselves. It is time to conduct a multi-national assessment of the North Pacific Ocean to develop a common, factual awareness of the threats looming over our coastal waters. Key words: contaminants, climate change, ecosystem change, monitoring, North Pacific, trends.


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