Inverse regional responses to climate change and fishing intensity by the recreational rockfish (Sebastes spp.) fishery in California

2004 ◽  
Vol 61 (12) ◽  
pp. 2499-2510 ◽  
Author(s):  
William A Bennett ◽  
Kimy Roinestad ◽  
Laura Rogers-Bennett ◽  
Les Kaufman ◽  
Deb Wilson-Vandenberg ◽  
...  
Keyword(s):  
Principal Component ◽  
Fishing Effort ◽  
Interactive Effects ◽  
Catch Per Unit Effort ◽  
The South ◽  
Annual Fish ◽  
Ocean Climate ◽  
The North ◽  
Regional Responses ◽  
Over Time

The interactive effects of ocean climate and fishing pressure on nearshore rockfishes (Sebastes spp.) were examined using historical commercial passenger fishing vessel catch records from California. Principal component analysis was used to characterize the dominant patterns in catch per unit effort (CPUE) over time (1957–1999) and space (10′ latitude × 10′ longitude blocks). Ocean climate explained 60% of the variation in CPUE and revealed opposite responses in northern and southern California. In warm El Niño years, CPUE was 4.2 times higher in the north and 1.8 times lower in the south. CPUE responded similarly to low-frequency climate shifts by increasing in the north and decreasing in the south after 1976–1977. Four geographic regions responded as discrete units to environmental forcing and fishing intensity: North, Central, South, and Channel Islands. Over time, annual fish landings declined sharply in the South, with fishing effort remaining stationary and high relative to that in the other regions. In the North, landings and fishing effort remained tightly coupled, with effort an order of magnitude lower than in the South. These findings support a management strategy for nearshore rockfishes in California based on regional responses to ocean climate and fishing intensity.

scholarly journals Heavy minerals in the Wajid Sandstone from Abha-Khamis Mushayt area, southwestern Saudi Arabia: implications on provenance and regional tectonic setting

GeoArabia ◽  
2004 ◽  
Vol 9 (4) ◽  
pp. 77-102 ◽  
Author(s):  
Mahbub Hussain ◽  
Lameed O. Babalola ◽  
Mustafa M. Hariri
Keyword(s):  
Saudi Arabia ◽  
Tectonic Setting ◽  
Principal Component ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Coarse Grained ◽  
Distribution Data ◽  
The South ◽  
Quartz Content ◽  
The North

ABSTRACT The Wajid Sandstone (Ordovician-Permian) as exposed along the road-cut sections of the Abha and Khamis Mushayt areas in southwestern Saudi Arabia, is a mediun to coarse-grained, mineralogically mature quartz arenite with an average quartz content of over 95%. Monocrystalline quartz is the dominant framework grain followed by polycrystalline quartz, feldspar and micas. The non-opaque heavy mineral assemblage of the sandstone is dominated by zircon, tourmaline and rutile (ZTR). Additional heavy minerals, constituting a very minor fraction of the heavies, include epidote, hornblende, and kyanite. Statistical analysis showed significant correlations between zircon, tourmaline, rutile, epidote and hornblende. Principal component R-mode varimax factor analysis of the heavy mineral distribution data shows two strong associations: (1) tourmaline, zircon, rutile, and (2) epidote and hornblende suggesting several likely provenances including igneous, recycled sedimentary and metamorphic rocks. However, an abundance of the ZTR minerals favors a recycled sedimentary source over other possibilities. Mineralogical maturity coupled with characteristic heavy mineral associations, consistent north-directed paleoflow evidence, and the tectonic evolutionary history of the region indicate a provenance south of the study area. The most likely provenances of the lower part (Dibsiyah and Khusayyan members) of the Wajid Sandstone are the Neoproterozoic Afif, Abas, Al-Bayda, Al-Mahfid, and Al-Mukalla terranes, and older recycled sediments of the infra-Cambrian Ghabar Group in Yemen to the south. Because Neoproterozic (650-542 Ma) rocks are not widespread in Somalia, Eritrea and Ethiopia, a significant source further to the south is not likely. The dominance of the ultrastable minerals zircon, tourmaline and rutile and apparent absence of metastable, labile minerals in the heavy mineral suite preclude the exposed arc-derived oceanic terrains of the Arabian Shield in the west and north as a significant contributor of the sandstone. An abundance of finer-grained siliciclastic sequences of the same age in the north, is consistent with a northerly transport direction and the existence of a deeper basin (Tabuk Basin?) to the north. The tectonic and depositional model presented in this paper differs from the existing model that envisages sediment transportation and gradual basin filling from west to east during the Paleozoic.

Fishing on floating objects (FOBs): how French tropical tuna purse seiners split fishing effort between GPS-monitored and unmonitored FOBs

2018 ◽  
Vol 75 (11) ◽  
pp. 1849-1858 ◽  
Author(s):  
Julia E. Snouck-Hurgronje ◽  
David M. Kaplan ◽  
Emmanuel Chassot ◽  
Alexandra Maufroy ◽  
Daniel Gaertner
Keyword(s):  
Search Time ◽  
Fishing Effort ◽  
Purse Seine ◽  
Trajectory Data ◽  
Catch Per Unit Effort ◽  
Position Information ◽  
Foreign Objects ◽  
Tropical Tuna ◽  
Floating Objects ◽  
Over Time

Fishing on floating objects (FOBs) dominates catch in tropical tuna purse seine fisheries. One frequently cited advantage of deploying GPS-monitored FOBs is that the position information can be used for directed fishing to reduce search time for tuna. However, purse seiners also fish on foreign objects for which position information is not available. It is critical to quantify the prevalence of fishing on GPS-monitored versus unmonitored FOBs to understand how they impact fishing effort and catch per unit effort. We analyzed French commercial, observer, and FOB trajectory data in the Atlantic and Indian oceans to determine how often purse seine vessels fish on GPS-monitored FOBs. Only 2.7%–20.4% of French FOB fishing sets over 2007–2013 in both oceans were made on GPS-monitored FOBs. Though increasing over time, the low percentage suggests that French vessels do not primarily use GPS-monitored FOBs to reduce search time for tuna. We hypothesize that fishery-wide FOB deployments have important collective consequences for overall fishing effort and recommend that future effort metrics should be based on fishery-wide FOB activities.

scholarly journals Multi-trait Analysis of Agroclimate Variations During the Growing Season in East-Central Poland (1971-2005)

2015 ◽  
Vol 29 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Elżbieta Radzka ◽  
Katarzyna Rymuza
Keyword(s):  
Principal Component Analysis ◽  
Air Temperature ◽  
Meteorological Data ◽  
Principal Component ◽  
Growing Season ◽  
Component Analysis ◽  
The South ◽  
East Central ◽  
Central Poland ◽  
The North

Abstract The work is based on meteorological data recorded by nine stations of the Institute of Meteorology and Water Management located in east-central Poland from 1971 to 2005. The region encompasses the North Podlasian Lowland and the South Podlasian Lowland. Average values of selected agroclimate indicators for the growing season were determined. Moreover, principal component analysis was conducted to indicate elements that exerted the greatest influence on the agroclimate. Also, cluster analysis was carried out to select stations with similar agroclimate. Ward method was used for clustering and the Euclidean distance was applied. Principal component analysis revealed that the agroclimate of east-central Poland was predominantly affected by climatic water balance, number of days of active plant growth, length of the farming period, and the average air temperature during the growing season (Apr-Sept). Based on the analysis, the region of east-central Poland was divided into two groups (areas) with different agroclimatic conditions. The first area comprized the following stations: Szepietowo and Białowieża located in the North Podlasian Lowland and Biała Podlaska situated in the northern part of the South Podlasian Lowland. This area was characterized by shorter farming periods and a lower average air temperature during the growing season. The other group included the remaining stations located in the western part of both the Lowlands which was warmer and where greater water deficits were recorded.

scholarly journals Solar cycle, seasonal, and asymmetric dependencies of thermospheric mass density disturbances due to magnetospheric forcing

2019 ◽  
Vol 37 (5) ◽  
pp. 989-1003 ◽  
Author(s):  
Andres Calabia ◽  
Shuanggen Jin
Keyword(s):  
Solar Cycle ◽  
High Frequency ◽  
Polar Region ◽  
Rotation Axis ◽  
Mass Density ◽  
Principal Component ◽  
Geomagnetic Variation ◽  
The South ◽  
The North ◽  
Possible Cause

Abstract. Short-term upper atmosphere variations due to magnetospheric forcing are very complex, and neither well understood nor capably modeled due to limited observations. In this paper, mass density variations from 10 years of GRACE observations (2003–2013) are isolated via the parameterization of annual, local solar time (LST), and solar cycle fluctuations using a principal component analysis (PCA) technique. The resulting residual disturbances are investigated in terms of magnetospheric drivers. The magnitude of high-frequency (δ < 10 d) disturbances reveals unexpected dependencies on the solar cycle, seasonal, and an asymmetric behavior with smaller amplitudes in June in the south polar region (SPR). This seasonal modulation might be related to the Russell–McPherron (RM) effect. Meanwhile, we find a similar pattern, although less pronounced, in the northern and equatorial regions. A possible cause of this latitudinal asymmetry might be the irregular shape of the Earth's magnetic field (with the north dip pole close to Earth's rotation axis, and the south dip pole far from that axis). After accounting for the solar cycle and seasonal dependencies by regression analysis to the magnitude of the high-frequency perturbations, the parameterization in terms of the disturbance geomagnetic storm-time index Dst shows the best correlation, whereas the geomagnetic variation Am index and merging electric field Em are the best predictors in terms of time delay. We test several mass density models, including JB2008, NRLMSISE-00, and TIEGCM, and find that they are unable to completely reproduce the seasonal and solar cycle trends found in this study, and show a clear overestimation of about 100 % during low solar activity periods.

scholarly journals Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean

2011 ◽  
Vol 68 (6) ◽  
pp. 1063-1071 ◽  
Author(s):  
Kuo-Wei Lan ◽  
Ming-An Lee ◽  
Hsueh-Jung Lu ◽  
Wei-Juan Shieh ◽  
Wei-Kuan Lin ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Net Primary Productivity ◽  
Principal Component ◽  
Yellowfin Tuna ◽  
Subsurface Water ◽  
Thunnus Albacares ◽  
Equatorial Atlantic ◽  
Catch Per Unit Effort ◽  
The North ◽  
Equatorial Atlantic Ocean

Abstract Lan, K-W., Lee, M-A., Lu, H-J., Shieh, W-J., Lin, W-K., and Kao, S-C. 2011. Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean. – ICES Journal of Marine Science, 68: 1063–1071. In this study, the Taiwanese longline (LL) fishery data were divided into two types: regular LL and deep LL. Furthermore, we collected environmental variables, such as sea surface temperature (SST), subsurface temperature, chlorophyll a concentration, net primary productivity, windspeed, and the north tropical Atlantic SST index (NTA) during the period 1998–2007 to investigate the relationship between LL catch data and oceanic environmental factors using principal component analysis (PCA). After the daily LL was separated into two types of LL, the results indicated that the deep LL was the major fishery catching yellowfin tuna (YFT) in the equatorial Atlantic Ocean. In 2003–2005, especially in 2005, the monthly catch by deep LL was double those of other years. The spatial distribution of the nominal catch per unit effort (cpue) by deep LL showed the maximum aggregation of YFT in waters with temperature above 24–25°C. The YFT mainly aggregated in the equatorial Atlantic, extending east in the first and second quarters of the year. In the third quarter of the year, the SST decreased off West Africa and the YFT migrated westwards to 15°W. Results of PCA indicated that higher subsurface water temperatures resulted in a deeper thermocline and caused a higher cpue of YFT, but the influence of NTA on the cpue of YFT seemed to be insignificant.

Who Left the South and How Did They Fare?

2016 ◽  
Author(s):  
Leah Platt Boustan
Keyword(s):  
Family Background ◽  
The South ◽  
Earnings Growth ◽  
Occupational Distribution ◽  
The North ◽  
The Family ◽  
Black Migrants ◽  
Southern Migrants ◽  
Over Time ◽  
Do So

This chapter shows that, for the southern blacks, migration is a route to economic advancement. To do so, the chapter first investigates the family background of black migrants leaving the South, revealing that young migrants living in the North in 1940 were drawn from households at both the top and the bottom of the occupational distribution. After arriving at their destinations, black migrants did not suffer an earnings penalty in the northern economy, but neither did they out-earn northern-born blacks as some have suggested. Rather, southern migrants earned just as much as northern-born blacks upon arrival in the North and experienced a similar pace of earnings growth over time.

scholarly journals Competition in the Promised Land: Black Migration and Racial Wage Convergence in the North, 1940–1970

2009 ◽  
Vol 69 (3) ◽  
pp. 755-782 ◽  
Author(s):  
Leah Platt Boustan
Keyword(s):  
Wage Growth ◽  
Elasticity Of Substitution ◽  
The South ◽  
Black Migration ◽  
Net Migration ◽  
Promised Land ◽  
The North ◽  
Black Economic ◽  
Skill Groups ◽  
Over Time

Four million blacks left the South from 1940 to 1970, doubling the northern black workforce. I exploit variation in migrant flows within skill groups over time to estimate the elasticity of substitution by race. I then use this estimate to calculate counterfactual rates of wage growth. I find that black wages in the North would have been around 7 percent higher in 1970 if not for the migrant influx, while white wages would have remained unchanged. On net, migration was an avenue for black economic advancement, but the migration created both winners and losers.

Differential attainment at school

2018 ◽  
pp. 65-80
Author(s):  
Stephen Gorard
Keyword(s):  
United Kingdom ◽  
School System ◽  
Moral Panics ◽  
The South ◽  
School Meals ◽  
Sensitive Measure ◽  
Free School ◽  
The North ◽  
The United Kingdom ◽  
Over Time

This chapter looks in more detail at some of the patterns of attainment in Chapter 3, such as by sex and area of residence. While these patterns change over time, all of them give further clues as to why the patterns themselves exist. As such, this chapter looks at some of the evidence on what were ‘moral panics’ at the time, such as the failure of pupils in Wales and the increasing under-achievement of boys and of parts of the United Kingdom. It also suggests that using the more sensitive measure of the duration of poverty (years with free school meals, or FSM) has much to recommend it. Using the number of years a student has been eligible for FSM, and how segregated a school system is by poverty and other indicators of disadvantage, it is possible to explain substantive differences such as the apparently superior attainment of schools in the South of England compared to the North.

scholarly journals Early evidence of the impact of preindustrial fishing on fish stocks from the mid-west and southeast coastal fisheries of Scotland in the 19th century

2015 ◽  
Vol 73 (5) ◽  
pp. 1404-1414 ◽  
Author(s):  
Peter Jones ◽  
Alison Cathcart ◽  
Douglas C. Speirs
Keyword(s):  
19Th Century ◽  
Fishing Effort ◽  
Ecosystem Change ◽  
Catch Per Unit Effort ◽  
The North ◽  
Mixed Approach ◽  
Long Term Impact ◽  
The 19Th Century ◽  
The Impact

Abstract In recent years, historical ecologists have turned their attention to the long-term impact of fishing on coastal marine ecosystems in the North Atlantic. Through the examination of non-traditional sources, scientists and scholars are beginning to piece together a clearer picture of ecosystem change over centuries of anthropogenic influence. One aspect of this long-term approach is that data are being recovered from some surprising sources, and, when placed alongside other evidence, are being used to create models of change through time where previously none would have been thought possible. Taking its lead from this work, our research takes a mixed approach to the history of Scotland's regional fisheries in the 19th century, combining the anecdotal evidence of fishers to parliamentary commissions of enquiry with data relating to landings and fishing effort which were gathered by the United Kingdom Fishery Board from 1809 onwards. As a result, it has been possible to calculate catch per unit effort (cpue) for the period between 1845 and the mid-1880s which, when placed alongside the direct evidence of fishers, lead to some unexpected conclusions. In particular, we demonstrate that inshore stocks of commercial whitefish appear to have been in decline by the mid-1850s in some areas, many years before the widespread adoption of beam trawling in Scotland; and we conclude that the most likely reason for this decline is the rapid intensification of fishing from open boats using the traditional techniques of handlines and longlines.

scholarly journals A Tale of Two Afghanistans: Comparative Governance and Insurgency in the North and South

Asian Survey ◽  
2010 ◽  
Vol 50 (4) ◽  
pp. 735-758
Author(s):  
Neil A. Englehart
Keyword(s):  
The South ◽  
Time And Space ◽  
Regional Variations ◽  
The North ◽  
History Of ◽  
North And South ◽  
Comparative Stability ◽  
Over Time

Afghanistan is often depicted as a failing state, but its failures display distinctive patterns over time and space. Regional variations in governance have been important in shaping the ways the Afghan state has failed and the consequences of these failures. This article argues that a history of better governance in the north facilitated the disarmament of militia warlords and comparative stability. By contrast, the south has a long history of minimal formal governance, creating opportunities for increased Taliban insurgency.

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