A voluntary reduction in the commercial catch of rock lobster (Jasus edwardsii) in a New Zealand fishery

We describe the development and application of a management procedure (decision rule) that resulted in a voluntary reduction in the commercial catch of spiny rock lobster (Jasus edwardsii) in the lower east coast of North Island of New Zealand. The management procedure was developed from an accepted assessment of the CRA 4 (Wellington‐Hawke's Bay) fishery, which used an integrated length‐based assessment model fitted to commercial fishery catch‐per‐unit‐effort (CPUE) biomass indices, commercial length‐frequency data, and tag‐recapture data. The assessment model had been Bayesian, and used the joint posterior distribution of parameters to predict the effect of 384 alternative harvest control rules on the future size of the CRA 4 stock. The harvest control rules all used CPUE as their input, and generated annual changes in catch, which were then simulated by the population dynamics of the operating model. Uncertainty was added to evaluations through observation error, added to the simulated CPUE observations, and stochastic serial auto‐correlation variation in recruitment. We describe how this management procedure was used to effect a voluntary reduction in catch to address the problem of a rapidly declining population.     

On the use of poorly soluble hygroscopic substances for modification of warm clouds and fogs

From analysis of the relationships between the equilibrium state of condensation nuclei and the relative humidity, a conclusion is made concerning the preferred use of poorly soluble substances for the generation of artificial condensation nuclei (ACN) designed for modification of warm clouds and fogs with the purpose of their dissipation and precipitation formation. The advantage of poorly soluble substances over commonly used soluble salts is that the finely dispersed part of the spectrum of the poorly soluble ACN does not deliquesce and so is not involved in the formation of cloud droplets. For experimental testing of the conclusions, preference was given to cement, whose main soluble substance is calcium oxide with a solubility of about 1 g/l. The spectrum of dispersed cement particles was measured and compared with the spectra of pyrotechnic flares widely used for modification at present. The process of formation of the cloud droplet spectra was simulated in the aerosol chamber of the Institute of Experimental Meteorology by decreasing the preliminarily generated excess pressure. It was found in these experiments that, compared to the spectra of particles formed on background condensation nuclei, the introduction of dispersed cement leads to the broadening of spectra and to a decrease in the concentration of droplets. Even at the early stage of condensation, droplets with radii of ∼20 μm appear. In this case, no “overseeding” phenomenon is observed, which, for soluble substances, manifests itself in an increase in the concentration of cloud droplets with a large ACN concentration. These effects indicate that, according to the existing concepts about the mechanism of warm-cloud modification with hygroscopic substances, the introduction of poorly soluble ACN (in particular, dispersed cement) below the base of cumulus clouds should stimulate coagulation processes and accelerate rain-formation processes. Considerations are given that the introduction of poorly soluble ACN into the already existing cumulus or stratocumulus clouds or fogs should also result in the acceleration of precipitation-formation processes or cloud dispersal. Comparison of cement powder with the well-known means of warm-cloud and fog modification is carried out. Original Russian Text ? N.P. Romanov, A.S. Drofa, N.S. Kim, A.V. Savchenko, G.F. Yaskevich, 2006, published in Izvestiya AN. Fizika Atmosfery i Okeana, 2006, Vol. 42, No. 1, pp. 80–91.     

Fully nonlinear numerical wave tank (NWT) simulations and wave run-up prediction around 3-D structures

A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.     

Deep tow studies of the Tamayo transform fault

The Tamayo transform fault occurs at the north end of the East Pacific Rise where it enters the Gulf of California. The two deep-tow surveys reported here show that the transform fault zone changes significantly as a function of distance from the spreading center intersections. At site 1, near the intersection, one side of the fault is young and the fault zone is narrow and well-defined. Strike slip occurs in a zone approximately 1-km wide suggesting a correspondingly narrow zone of decoupling between the Pacific and North American plates. On the young side of the strike-slip zone, normal faults occur along shear zones which are 45°–50° oblique to the transform strike. They occur parallel to the short axis of the strain ellipse for transform fault strain here, i.e., perpendicular to the least compressive stress. The transform walls are formed by normal faulting as has been pointed out in previous detailed surveys. Here, however, the age contrast of 2.5 m.y. across the transform valley is apparent in the morphology of the normal fault scarps. While the scarps are steep and well-defined on the young side, the scarps on the older side have gradual 10°–30° slopes and appear to be primarily talus ramps. Apparently, the scarps have been tectonically eroded by continued strike slip activity after the initial stages of normal faulting. Thus, transform valleys should be quite asymmetric in cross-section where there is a significant age contrast and one side is less than approximately 0.5 m.y. old. Also, along older sections of the transform valley walls, normal faulting may not be at all obvious due to degradation of the scarps by tectonic erosion. This phenomenon makes the likelihood of transform faults providing windows into the oceanic crust most unlikely except in special cases.The picture of transform deformation is more complex at site 2 in the central portion of the fault where both sides of the fault are greater than 1 m.y. old. Here the transform valley is wider (25–30 km as opposed to 2–5 km). There is no clear simple zone of strike slip tectonics. In fact, the only clear evidence for deformation is the intrusion of magmatic or serpentinite diapirs through the sediments of the transform valley floor. The diapirs have deformed the turbidite layers flooring the valley and in one carefully studied case the turbidite sequence has been uplifted, perched atop the diapir. The pattern of deformation on this outcropping diapir shows radial and concentric fractures which can be modeled by a vertical intrusion circular in plan view. Magnetic studies limit the possible composition to basalt or serpentinite. A 60-km-long median ridge is also likely to be the product of intrusion along the transform fault. The survey at site 2 pointed out the importance of vertical tectonics in the transform valley floor and in particular the importance of diapiric intrusions of either basaltic or serpentinite composition.Based on initial boundary conditions and present tectonic elements in the Tamayo fault zone, a possible history of the mouth of the Gulf of California is outlined. The median ridge was emplaced starting approximately 0.8 m.y. ago by regional extension across the transform fault, the result of leaky transform faulting. The diapirs occur along a possible relay zone of extension midway along the fault which began approximately 0.15 m.y. ago. The extension in this case is parallel to the trend of the transform fault, is still occurring at present, and may evolve into a true spreading center.Contribution of the Scripps Institution of Oceanography, new series.     

Application of probabilistic neural network to design breakwater armor blocks

This study presents a probabilistic neural network (PNN) technique for predicting the stability number of armor blocks of breakwaters. The PNN is prepared using the experimental data of Van der Meer. The predicted stability numbers of the PNN are compared with those of previous studies, i.e. by an empirical formula and a previous neural network model. The agreement index between the measured and predicted stability numbers by PNN are better than those by the previous studies. The PNN offers a way to interpret the network's structure in the form of a probability density function and it is easy to implement. Therefore, it can be an effective tool for designers of rubble mound breakwaters.     

Population structure of the Korean gizzard shad, <Emphasis Type="Italic">Konosirus punctatus</Emphasis> (Clupeiformes,Clupeidae) using multivariate morphometric analysis

The gizzard shad, Konosirus punctatus, is one of the most important fish species in Korea, China, Japan and Taiwan, and therefore the implementation of an appropriate population structure analysis is both necessary and fitting. In order to clarify the current distribution range for the two lineages of the Korean gizzard shad (Myoung and Kim 2014), we conducted a multivariate morphometric analysis by locality and lineage. We analyzed 17 morphometric and 5 meristic characters of 173 individuals, which were sampled from eight localities in the East Sea, the Yellow Sea and the Korean Strait. Unlike population genetics studies, the canonical discriminant analysis (CDA) results showed that the two morphotypes were clearly segregated by the center value “0” of CAN1, of which morphotype A occurred from the Yellow Sea to the western Korean Strait with negative values, and morphotype B occurred from the East Sea to the eastern Korean Strait with positive values even though there exists an admixture zone in the eastern Korean Strait. Further studies using more sensitive markers such as microsatellite DNA are required in order to define the true relationship between the two lineages.     

Vertical distribution of giant jellyfish, <Emphasis Type="Italic">Nemopilema nomurai</Emphasis> using acoustics and optics

Nemopilema nomurai jellyfish, which are believed to complete their development in the East China Sea, have started migrating into the Yellow Sea in recent years. We obtained biomass estimates of this species in the Yellow Sea using bottom trawl fishing gear and sighting surveys over a 5-year period. These methods are effective for obtaining N. nomurai jellyfish density estimates and information about the community distribution near the bottom or surface of the sea. To verify the vertical distributions of giant jellyfish between, we used hydroacoustic equipment, including an optical stereo camera system attached to a towed sledge and an echo counting method with scientific echosounder system. Acoustic and optical data were collected while the vessel moved at 3 knots, from which the distribution and density of N. nomurai jellyfish were analyzed. Subsequently, the camera system was towed from a 7 m mean depth to sea level, with the detection range of the acoustic system extending from an 8 m depth to the bottom surface. The optical and acoustic methods indicated the presence of vertical distribution of 0.11³ (inds/m³) and 0.064 (inds/m3), respectively. However, the vertical distribution indicated that around 93% of individuals occurred at a depth range of 10–40 m; thus, a 2.4-fold greater density was estimated by acoustic echo counting compared to the optical method.     

Genetic stock identification of immature chum salmon (<Emphasis Type="Italic">Oncorhynchus keta</Emphasis>) in the western Bering Sea, 2004

Genetic stock identification studies have been widely applied to Pacific salmon species to estimate stock composition of complex mixed-stock fisheries. In a September-October 2004 survey, 739 chum salmon (Oncorhynchus keta) specimens were collected from 23 stations in the western Bering Sea. We determined the genetic stock composition of immature chum salmon based on the previous mitochondria DNA baseline. Each regional estimate was computed based on the conditional maximum likelihood method using 1,000 bootstrap resampling and then pooled to the major regional groups: Korea - Japan - Primorie (KJP) / Russia (RU) / Northwest Alaska (NWA) / Alaska Peninsula - Southcentral Alaska - Southeast Alaska - British Columbia - Washington (ONA). The stock composition of immature chum salmon in the western Bering Sea was a mix of 0.424 KJP, 0.421 RU, 0.116 NWA, and 0.039 ONA stocks. During the study period, the contribution of Asian chum salmon stocks gradually changed from RU to KJP stock. In addition, North American populations from NWA and ONA were small but present near the vicinity of the Russian coast and the Commander Islands, suggesting that the study areas in the western Bering Sea were an important migration route for Pacific chum salmon originating both from Asia and North America during the months of September and October. These results make it possible to better understand the chum salmon stock composition of the mixed-stock fisheries in the western Bering Sea and the stock-specific distribution pattern of chum salmon on the high-seas.     

Molecular phylogeny of the families Pleuronectidae and Poecilopsettidae (PISCES,Pleuronectiformes) from Korea,with a Proposal for a new classification

A new classification of the Korean pleuronectids was proposed based on a molecular phylogeny using specimens collected from Korea (including some Japanese specimens) between 2008 and 2013. A molecular phylogeny based on partial sequences of the two mitochondrial DNA regions (COI and 16S rRNA) supported the reciprocal monophyly of the three genera, Cleisthenes, Pleuronectes and Pseudopleuronectes. We also found that the genus Poecilopsetta is clearly distinct from Pleuronectidae at the family level. Therefore, the previous classification of the Korean pleuronectids should be changed as follows; two families (Pleuronectidae and Poecilopsettidae), 18 genera, and 26 species. Further research is required to resolve the taxonomic uncertainty of the five species in the genus Limanda, which clustered into two clades in our analysis.     

Age and growth of filefish, <Emphasis Type="Italic">Thamnaconus modestus</Emphasis> (Günther, 1877) off the Jeju Island of Korea

The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL^3.0536 (n = 1,692, r² = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5^th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L_∞ = 42.04 cm, k = 0.21 year^?1 and t₀ = ?1.56 for females, L_∞ = 41.20 cm, k = 0.18 year^?1 and t₀ = ?2.36 for males, and L_∞ = 43.16 cm, k = 0.17 year^?1 and t₀ = ?2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.