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Luzenczyk A.,Polish National Marine Fisheries Research Institute
Acta Ichthyologica et Piscatoria | Year: 2017

Background. In this study, the relation between the biological reference points (BRPs) associated with Maximum Sustainable Yield (MSY) and the relevant biological, fisheries, and environmental factors were investigated. This knowledge is crucial to build the capacity for timely adaptation of management to the changes in an ecosystem. The research highlights the considerations that need to be taken into account when estimating and using BRPs in practice, and can thus lead to avoidance of overfishing. The BRPs were represented by MSY and the related spawning stock biomass (BMSY), fishing mortality (FMSY), and FMSY proxies. Materials and methods. To obtain the BRPs, the method of Horbowy and Luzeńczyk (2012)—that combines yield-per-recruit and spawning stock-per-recruit analyses with stock-recruitment relation models (Beverton and Holt (B&H) 1957, Ricker 1975)—was used. Data from the three biggest Baltic Sea stocks were used to test the sensitivity of BRPs to the model input data, and the influence of regime shifts or dynamics of the biological and fisheries variables on the BRPs. Results. The analyses show that an increase in maturity and weight at age generally led to an increase in BRPs. The opposite effect is observed in the case of natural mortality (stronger when the Ricker stock–recruitment (S–R) relation was used) and selectivity (proportion of the F of partially recruited age groups to the mean F of fully recruited age groups). An increase in the steepness of S–R models increases FMSY and its proxies as well as MSY, and had a decreasing influence on BMSY. Furthermore, the BRPs are very sensitive to the different data range divisions of the input data. Conclusion. When estimating BRPs, the time period of the input data should be selected with caution, and the appropriate time period should be based on strong biological, ecological, and environmental knowledge as, according to this study, all of these factors influence estimates of BRPs. © 2017, Scientific Society of Szczecin. All rights reserved.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Food Control | Year: 2015

Background: Mercury content in fish poses risks to the fish and to those who consume them. The aim of the current study was to verify the protective role of selenium against toxic mercury in Baltic fish. The assessment criteria were the Se:Hg molar ratio, its variability depending on species and tissue, and correlations among Se:Hg ratios, mercury concentration, and specimen length. Assays were performed in muscle and liver tissues of Baltic Sea commercial fish species, i.e., cod, herring, sprat, plaice, and turbot. Results: Mercury concentrations in fish from the Baltic Sea are at low level. The values of the Se:Hg molar ratio were higher than 1 (with the exception of a few cod specimens), with ranges in muscle tissues as follows: cod 0.75-28.2; herring 2.0-50.3; sprat 14.2-56.2; flatfish 1.5-35.1; and in livers as follows: cod 10.9-268.2; herring 10.7-87.1; flatfish 10.2-232. The values of the Se:Hg ratio in muscle and liver tissues were negatively correlated with mercury content and specimen length. Conclusion: Mercury concentrations in commercial fish from the Baltic Sea are low and do not pose risks to consumers. The high values of the Se:Hg molar ratio confirm that mercury levels are safe, and also that selenium might offer protection against methylmercury toxicity, which could increase the safety of fish consumption. The values of the Se:Hg molar ratio could be an additional criterion, in addition to measuring Hg concentrations, for evaluating the risk of mercury exposure in fish from the Baltic Sea. © 2014 Elsevier Ltd.

Horbowy J.,Polish National Marine Fisheries Research Institute
Fisheries Research | Year: 2011

Management strategy evaluation (MSE) was used to test the assessment and management performance of three assessment methods in combination with harvest control rules. The assessment procedures considered were: the eXtended Survivors Analysis (XSA), the Schaefer production model, and the difference model. Four HCRs were considered: first, fishing mortality was set on the basis of the relationship between the current biomass and a reference biomass; second, fishing mortality was gradually reduced (or increased) until it reached a required target; and the third and the fourth HCRs were similar to the first and second but with imposed TAC constraints. The stock that was generated in the operating model (OM) resembled the eastern Baltic cod stock. For the XSA assessment, two options were used: XSA with default shrinkage of terminal fishing mortality to the average of the estimates, and XSA with low shrinkage. The simulations showed that for stock assessment, the XSA models performed much better than the difference and Schaefer models. However, for the data tested, the difference and Schaefer models performed somewhat better in terms of management performance than the XSA models, especially the XSA model with default shrinkage. © 2010 Elsevier B.V.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Chemosphere | Year: 2011

A study was conducted to examine spinal deformities such as lordosis, scoliosis, and dwarfism in cod (Gadus morhua callaris L.) that were caught in the southern Baltic. The bone tissue of the spine and the muscle of the deformed cod were analyzed for concentration of macroelements (Sr, Ca and P) and toxic metals (Cd, Pb and Hg). Healthy specimens of the same body length that were caught in the same hauls were also tested, and these comprised the reference material. The study was undertaken to verify the hypothesis that lowered values of Ca/Sr and P/Sr ratios caused skeletal deformities. Toxic metals were also tested to determine whether they had an impact on the deformities of cod inhabiting Baltic waters. In cod with deformities, a significant decrease in Ca/Sr ratios were noted in 86% of the spine and 97% of the muscle. Decreases in the values of the P/Sr ratios were confirmed in 57% of the bone tissue and 78% of the muscle tissue of individuals with skeletal deformities. Toxic metals (Cd, Pb and Hg) occurred in the bone and muscle tissues of deformed and healthy cod on the low levels. It was not differences in concentrations of these elements, and thus could not have had an impact on the occurrence of deformities. Skeletal deformities could have resulted from lowered values of the Ca/Sr and P/Sr ratios of the spinal bone and muscle tissues of cod. Lower values of these coefficients should be linked to the varied salinity (5-21‰) and strontium (5-15Bqm-3) concentrations of Baltic waters. © 2010 Elsevier Ltd.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Chemosphere | Year: 2012

Mercury concentrations in three flatfish species - flounder (Platichtys flesus), plaice (Pleuronectes platessa), and Baltic turbot (Scophthalmus maximus), netted in the southern Baltic Sea were assessed and compared to concentrations of this metal in sediments, sea water, and flatfish food - bivalve Macoma balthica, isopod Saduria entomon, and sprat (Sprattus sprattus). Collected simultaneously with flatfish in 2009 and 2010. Different concentrations of mercury depending on species, tissue or organ, sex, individual length, kind of food, and region were determined. The muscle tissues of turbot had the highest concentrations of the metal. The bioaccumulation (BF) and biomagnification (BMF) factors has been counted showing that the muscle tissues of turbot have maximum affinity for mercury, and thus best reflected the metal contamination of the Baltic Sea environment. The data suggest that the common Baltic turbot (S. maximus) is an important model species, suitable and cost-effective to biomonitor environmental mercury pollution for ecological research. © 2012 Elsevier Ltd.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Environmental Science and Pollution Research | Year: 2013

Trace metals were examined in the muscle tissue of flatfish species of flounder, Platichthys flesus (Linnaeus, 1758), sediments from two southern Baltic Sea sites (Gdańsk Bay and Ustecko-Łebskie as a reference) and in two areas of the Portuguese Atlantic coast (Douro River estuary and Atlantic fishing ground as a reference) to evaluate spatial differences in trace metals. Additionally, the accumulation of trace metals in flounder of different length classes was assessed. Flounder from the Gdańsk Bay area contained twofold more cupper (Cu), lead (Pb) and mercury (Hg) than did flounder from the Douro River estuary, but zinc (Zn) and cadmium (Cd) were at similar concentrations. The sediments from Gdańsk Bay contained significantly more Zn and threefold more Cd, while concentrations of Cu and Pb were twofold lower. The concentrations of metals in the sediments did not correlate with those in the flounder. Spatial differences were noted in metal concentrations in flounder from the southern Baltic Sea and the Portuguese Atlantic coast as well as within these regions, with higher concentrations in the flounder from the Baltic Sea Gdańsk Bay. The flounder in length class 25-30 cm from Gdańsk Bay contained metal concentrations comparable to those of class 40-45 cm specimens from the Atlantic coast. The accumulation of metals in flounder length classes differed in the two regions. © 2013 Springer-Verlag Berlin Heidelberg.

Sokolowska E.,Polish Academy of Sciences | Fey D.P.,Polish National Marine Fisheries Research Institute
Journal of Fish Biology | Year: 2011

The ages of 8 to 23.5 cm total length (LT) round goby Neogobius melanostomus collected monthly during 2006 and 2007 in the Gulf of Gdańsk (Baltic Sea) ranged from 2 to 6 years, with age class 4+ years dominant. Males were larger at age than females. The fastest growth occurred in the first 2 years of life in both sexes. Females were heavier at a given LT than males, but only for fish > c. 15 cm. A strong relationship between N. melanostomus otolith size and fish size was found, with no difference between males and females, and a significant relationship between fish growth rate and otolith growth rate, which enabled backcalculation of growth rates. Marginal increment width analysis confirmed the periodicity of annual ring formation in otoliths and showed that the most intense opaque zone formation occurs in July to August, while hyaline zone formation starts as early as September to October. It was concluded that the N. melanostomus that have colonized the southern Baltic Sea exhibit the largest size and longest life span ever recorded for this species. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Environmental Monitoring and Assessment | Year: 2013

This paper presents and discusses the levels and temporal trends of concentrations of Cd, Pb, Hg, Cu, Zn, and As in livers and Hg in the muscle tissues of cod (Gadus morhua L) from the Baltic Sea during the period 1994-2010. Concentrations of Pb, Hg, and Cd exhibited significant downward trends. Cu and Zn concentrations exhibited upward trends in the period 1994 to 2010. No trends were detected for concentrations of As. The temporal trends identified in heavy metal concentrations in cod livers corresponded to the directions of changes in concentrations of these elements introduced into the Baltic Sea via river runoff and atmospheric emission, and those in surface and deep waters of the Baltic. Downward trends in the concentrations of toxic metals in cod livers suggest that advantageous changes are occurring in concentrations of heavy metals in the environment of the southern Baltic Sea. © 2012 Springer Science+Business Media B.V.

Kornijow R.,Polish National Marine Fisheries Research Institute
Journal of Paleolimnology | Year: 2013

The new sediment slicer described herein provides an easy and time-efficient way of sectioning cores of varying length, diameter, and composition from a wide range of habitats and sediment types. It is designed to process sediments collected by means of any soft-sediment core sampler with the core tube detachable from the sampler head and trigger unit. It is useful for sectioning core samples that include both the undisturbed sediment/water interface and highly consolidated sediments. The slicer is composed of three parts: (1) a supporting block, (2) a gliding block with the incorporated 10 cm sub-sampler holder designed to glide freely in the grooves along the supporting block, and (3) a metal blade for sediment slicing. © 2012 Springer Science+Business Media Dordrecht.

Polak-Juszczak L.,Polish National Marine Fisheries Research Institute
Journal of Toxicology and Environmental Health - Part A: Current Issues | Year: 2010

This study determined the concentrations of copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) in flounder from the southern Baltic for the 1996-2003 period. Analysis of more than 200 samples was used to determine the following: (1) concentrations of Hg and As in muscle tissue of flounder from different regions of the southern Baltic; (2) concentrations of Hg in the muscle tissue of flounder of different sizes; and (3) temporal trends in the concentrations of trace metals during the 1996-2003 period. A positive correlation between fish length and Hg concentration was noted. Further, the concentrations of Hg and As in flounder were correlated with sampling site. The most heavily polluted region of the Polish Baltic zone was the eastern region of the Baltic Sea. The temporal trend analyses showed significant downward trends in concentrations of Cd, Hg, and Pb in the flounder from the 1996-2003 period. Data suggest a decrease in the concentration of these elements in the environment of the Polish zone of the Baltic. It is noteworthy that no upward trends were noted in the concentrations of trace metals in the fish studied. If the flounder selected for the study are recognized as bioindicators of environmental pollution, then it is possible to conclude that the changes in trace metals concentrations in the Polish zone of the Baltic Sea are being reduced. Copyright © 2010 Taylor and Francis Group, LLC.

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